US Secretary of State Hillary Clinton urged India on Wednesday to be more assertive in Asia, reflecting US desire for New Delhi to emerge as a counter-weight to Chinese power.

Speaking in the Indian city of Chennai -- a southern trading port looking out towards east Asia -- Clinton argued that India needed to play a bolder leadership role in building security and prosperity in the region.

"India's leadership has the potential to positively shape the future of the Asia-Pacific... and we encourage you not just to look east, but continue to engage and act east as well," she said in Chennai.

Washington has actively courted India, regarding the country as a natural ally because of the two countries' shared belief in democracy, human rights and market-oriented economic policies.

"This is not a time when any of us can afford to look inward at the expense of looking outward," she added. "This is a time to seize the emerging opportunities of the 21st century. This is a time to lead."

China, militarily and economically superior to India, is Asia's dominant power and has been spreading its influence into India's immediate neighbourhood, notably in Sri Lanka and Nepal.

Beijing has also been involved in several incidents in the disputed South China Sea, which is believed to be rich in oil and gas, leading to fears it is prepared to assert its power more forcefully.

Clinton stressed that India should play a role as a US ally in regional forums such as the Association of Southeast Asian Nations (ASEAN) and a planned East Asia Summit later this year.

She made only one explicit mention of China in the speech, saying that she was "committed to a strong, constructive relationship" between Washington, New Delhi and Beijing.

But alongside the praise and advocacy for India, Clinton returned to the issue of New Delhi's stance on human rights abuses in Asia, which was also highlighted by US President Barack Obama in his visit to the country last year.

India has formed close ties with military-ruled Myanmar, a northeastern neighbour, and the US believes New Delhi should exert more pressure on its generals over the country's record.

"As India takes on a larger role throughout the Asia-Pacific, it is also taking on new responsibilities including the duty to speak out against violations of universal human rights," she said.

Although Washington wants to promote India as a leader in Asia, some commentators have questioned the country's willingness and capability to step into the role.

Writing in the Wall Street Journal on Wednesday, Sadanand Dhume from the American Enterprise Institute in Washington said that India had failed to prevent a slide into authoritarianism in neighbouring Sri Lanka.

"This raises an awkward question about India's quest for great-power status. Simply put, how can India expect more clout on the world stage when it wields so little influence in its own neighborhood?" he wrote.

On Tuesday, Clinton met Indian leaders in New Delhi including Prime Minister Manmohan Singh and Foreign Minister S.M. Krishna to push for easier access to the country's nuclear market and closer security cooperation.

She stressed that the US-India relationship, which President Barack Obama described as the "defining partnership of the 21st century", had made great progress in recent years, but was yet to fulfill its potential.

The top diplomat singled out civil nuclear energy as an area where the countries "can and must do more" amid frustrations that private US nuclear energy firms are losing out to their French and Russian competitors.

As well as lobbying for US commercial interests, the trip to India is also about balancing the delicate relationships Washington maintains with violence-wracked South Asian countries.

Clinton said she was "encouraged" by India and Pakistan's decision to restart their stop-start peace process, but she also heard Indian worries that a planned US troop drawdown in Afghanistan could lead to instability.