China said Tuesday it condemned any kind of violence against civilians after a twin bombing killed at least three people and injured more than 140 others, including a Chinese student, at the Boston Marathon on Monday.

Analysts said the attack, the most deadly bomb attack on US soil since September 11, 2001, is likely to impact the anti-terrorism and military strategies of the Obama administration, which in recent times has been more focused on cyber security.

Chinese President Xi Jinping Tuesday expressed sympathy and condolences to the US government and people in a phone talk with US President Barack Obama.

"China strongly condemns and is firmly opposed to any attack aimed at civilians," Chinese foreign ministry spokeswoman Hua Chunying said Tuesday.

The Chinese Consulate General in New York confirmed to the Global Times that one female Chinese student was injured in the accident and they have already sent personnel to visit the student in hospital.

A total of 87 Chinese nationals were registered for the marathon, according to the Xinhua News Agency.

In Boston, US federal investigators on Tuesday were still hunting for clues that could lead them to those responsible for the bombing.

The Boston Globe reported that among the dead was 8-year-old Martin Richard, whose mother and sister were also severely injured.

Investigators were still searching for undetonated explosive devices and fragments of bombs after they already found what could be five additional bombs that did not go off around the Boston area, the Wall Street Journal said.

The two bomb devices, using gunpowder as the explosive, were packed with ball bearings and other shrapnel to maximize the damage they incurred, Reuters quoted a senior law enforcement official as saying.

So far no person or group has claimed responsibility for the attack and investigators have yet to determine whether the attack was launched by a home-grown lone-wolf extremist or orchestrated by foreign terrorist organizations.

"The attack, characterized by a twin bombing specifically targeting civilians, is similar to terror blasts occurring in countries such as Iraq and Afghanistan, and therefore was more likely planned by international terror groups," Li Wei, director of the Institute of Security and Arms Control Studies with the China Institute of Contemporary International Relations, told the Global Times, noting that home-grown extremists tended to choose government buildings and officials as their targets.

The Pakistani Taliban, which claimed to have had a role in the 2010 Times Square car bomb plot, denied any involvement in the killings.

"We have no connection to this bombing but we will continue to target them wherever possible," Tehreek-e-Taliban Pakistan spokesman Ehsanullah Ehsan told AFP.

After the attack, Obama chose carefully not to mention the word "terrorism" in a briefing in which he vowed to hunt down the responsible.

"We will get to the bottom of this and we will find out who did this. Any responsible individuals, any responsible groups will feel the full weight of justice," he said.

If it is finally proved that a foreign country-based terror group was behind the attack, this might force the Obama administration to change some of its anti-terrorism and military strategies, Li said.

James Clapper, director of US National Intelligence, said for the first time last month that cyber attacks pose a greater potential danger than Al Qaeda and are now the top threat to US national security.

"The US may have to remake its evaluations of national security now after the Boston attack and adjust its anti-terror and military cooperation with some nations," Li noted.

"The increase in security, not just in Boston but in other major cities, will mitigate the risk of further attacks in the coming days," said a note sent to the Global Times Tuesday by Exclusive Analysis, a London-based risk forecasting company.

Agencies contributed to this story

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