US Secretary of State Antony Blinken arrives for a G20 foreign and development ministers meeting in Matera on Tuesday. Photo: VCG

US Secretary of State Antony Blinken issued a veiled warning Wednesday about Indian democracy backsliding in his first official visit to New Delhi.

Rights groups say civil liberties and the space for dissent are under increasing attack in the world's biggest democracy under Prime Minister Narendra Modi's government.

Blinken told civil society groups - his first appointment before meeting Foreign Minister Subrahmanyam Jaishankar and Modi - that the US and India are "connected by shared values" such as rule of law and freedom of religion.

But he added: "Both of our democracies are works in progress... As I said before, sometimes that process is painful. Sometimes it's ugly. But the strength of democracy is to embrace it."

"At a time of rising global threats to democracy and international freedoms - we talk about a democratic recession   - it's vital that we two world-leading democracies continue to stand together in support of these ideals." Under Modi, India has made growing use of anti-terrorism legislation and "sedition" laws to arrest campaigners, journalists, students and others, critics say.

Earlier this month, an 84-year-old priest and tribal rights activist, charged with terrorism offences, died after nine months in custody, prompting international outrage including from the UN High Commissioner for Human Rights.

The Hindu nationalist administration has also brought in legislation that detractors say discriminates against India's 170-million-strong Muslim minority.

The government denies cracking down on criticism and says people of all religions have equal rights.

Biden has further riled New Delhi with Washington's "rushed and poorly planned exit from Afghanistan," Chellaney added.

India is worried that a possible takeover by the Taliban, which it sees as backed by its arch-rival Pakistan, will turn the country into a base for militants to attack India.

The Taliban welcomed virulently anti-Indian extremists when the Sunni Muslim militants ruled Afghanistan from 1996 to 2001.

India, on course to become the planet's populous country, is the world's third-biggest carbon emitter and is on the front line of the ravages of global warming."