Since GlaxoSmithKline (GSK) announced a deal to produce HIV medicine with Shanghai firm Desano Pharmaceuticals in July, Britain's biggest drug maker is taking more steps to repair its scandal-hit business in China.

"I hope we can come out of the shadow of that," said Andrew Witty, chief executive of the pharmaceutical conglomerate in an exclusive interview with Xinhua ahead of Chinese President Xi Jinping's state visit to Britain.

Chinese authorities fined GSK China a record 3 billion yuan (297 million pounds) in September last year for bribing doctors, and executive Mark Reilly was handed a suspended prison sentence.

"It was a very sad and challenging period for us. We have worked very hard to learn lessons from that," said Witty.

Though the bribery case has hit GSK's sales in China, the British drug giant still sees the country as an important source of future revenue.

"Our strategy is undiminished commitment to long-term investment to China," Witty told Xinhua.

The anti-corruption probe against GSK, together with anti-monopoly investigations against Microsoft, Jaguar Land Rover, and Qualcomm, stirred unease among foreign firms who perceived unfair treatment and a worsening investment environment.

However, Chinese authorities repeatedly said that the anti-monopoly and anti-corruption probes will bring a fairer, non-discriminatory business environment to help pave the way for further opening-up.

"I think the big message for also many others in China is that China changes all the time, and it's really important to keep listening to the voice of China," said Witty. "We have to understand the regulations, we have to abide by the regulations,"

Chen Fengying, a research fellow with the China Institutes of Contemporary International Relations, said the market economy is essentially an economy under rule of law.

"To ensure the market's decisive role in allocating resources, the Chinese government should adopt a zero-tolerance policy toward corruption," said Chen.

Economists also believe the anti-graft fight could benefit foreign companies operating in China as it will improve business practices.

"Anti-corruption helps the economy in the long run, as it reduces business costs," said Chang Jian, chief China economist with Barclays Plc in Hong Kong. "Just like corporate restructuring, it brings short-term effects but has benefits in the future."

As part of an effort to rebuild its image, GSK has announced major changes in its sales and marketing practices, according to Witty.

Particularly noteworthy was that GSK no longer ties the compensation of its sales representatives to the number of prescriptions written by the doctors they interact with. Instead, GSK sales reps will be paid based on their technical knowledge and the quality of service they provide to their clients.

"Some people are questioning the presence here, honestly, I believe they are making short-term decisions," said the GSK CEO, noting that the company will invest more in China.

The steady economic growth in China and Britain is a bright spot in a gloomy global economy. In the first eight months of this year, China-Britain trade volume reached 50.6 billion US dollars, according to statistics from Chinese Ministry of Commerce.

Britain has become China's second largest investor and trading partner within the European Union. As of August, Britain had invested in 7,992 projects in China, with an actual investment of 19.61 billion US dollars.

"It is a good time to invest in China, to learn and understand what the new normal really means in China, and to work with China to deliver good value to its people, then the company will do fine in China," said Witty, who is optimistic about China's economic prospects.

Ralf Speth, CEO of Jaguar Land Rover, also voiced confidence in the growth of the Chinese market in September.

Jaguar Land Rover, a British luxury car brand owned by India's Tata Motors, sold 122,010 cars in China last year, up 28 percent from 2013. The company also cited the Chinese market as the primary reason for its fifth successive year of growth in global sales.

The automotive industry is vital to the British economy. It has an annual turnover of over 60 billion pounds (88.43 billion US dollars). Around 770,000 jobs depend on the industry, data from the Society of Motor Manufacturers and Traders Limited (SMMT) showed.

China has taken a number of steps to provide easier market access for inbound foreign investment and explore the possibility of management based on a pre-establishment national treatment (PENT) and negative-list approach, which means all sectors are open to foreign investment except those specifically listed.

PENT means that foreign investors and their investments will be accorded national treatment in the pre-establishment phase of their businesses. "Negative list" refers to activities to which national treatment and most favored nation status do not apply.

"By so doing, we aim to address the legitimate concerns of foreign investors in a timely manner, protect their lawful rights and interests, and foster a level playing field with open and transparent laws and policies, along with a more efficient administration," said Chinese President Xi Jinping in a written interview with the Wall Street Journal last month.

According to surveys by the UN Conference on Trade and Development (UNCTAD) and other authoritative international bodies, China remains the world's most attractive investment destination.

Claims about a changing investment climate in China and foreign investors losing confidence in China are not backed by facts.

In 2014, China received 120 billion US dollars in foreign investment, more than any other country, and continued to be the leading destination among developing countries for 23 years running.

In the first eight months of this year, the actual amount of foreign investment used by China totaled 85.3 billion dollars, up nine percent from the corresponding period of the previous year.

"We welcome all foreign companies in China and will respect and protect their lawful rights and interests provided that they abide by the laws and regulations of China and do nothing to undermine China's national interests and interests of Chinese consumers," said Xi.

Witty noted that businesses in China should be committed to long-term objectives. "You can't be in China on Monday, and not in China on Wednesday and back on Friday. You have to be in China," he said.

On September 23, GSK announced its plan to fund programs under China's National Health and Family Planning Commission to train about 13,000 physicians in the prevention and treatment of chronic obstructive pulmonary disease (COPD) and chronic hepatitis B over the next five years.

"We have been in here for a hundred years, we have ups and downs, but we continue to expand our offer, we continue to make clear that we will do more here," said Witty.