COLOMBO (Reuters, AFP) - US Secretary of State John Kerry said on Saturday the United States wanted to renew ties with Sri Lanka and announced the start of an annual bilateral dialogue after years of tensions with the island nation's former government.

Kerry arrived in the South Asian country earlier on Saturday, the first time in a decade that a US Secretary of State has visited Sri Lanka.

Washington had years of tensions over human rights with former President Mahinda Rajapaksa, who was unseated by Mathripala Sirisena in a surprise election win in January.

Sri Lanka had also tilted heavily towards China as Rajapaksa fell out with the West over human rights and allegations of war crimes at the end of the government's drawn-out conflict with Tamil separatists, which ended in 2009.

Kerry said Washington wanted to work with Sirisena and lauded the new government's efforts to tackle corruption, build democratic institutions and address the wrongs of the past through a process of national reconciliation.

"I am here today because I want to say to the people of Sri Lanka in this journey to restore democracy the American people will stand with you," Kerry said after meeting Sri Lanka Foreign Minister Mangala Samaraweera. "We intend to broaden and to deepen our partnership with you," Kerry said while announcing the annual dialogue.

Samaraweera called Kerry's visit a "momentous occasion" and said it "signified the return of our little island nation to the centre stage of international affairs".

Kerry has been credited in Sri Lanka for his role in pressing for peaceful and inclusive elections, and for calling Rajapaksa on the eve of voting to urge him to respect the outcome.

Kerry was due to meet Sirisena later on Saturday as well as Prime Minister Ranil Wickremesinghe and Rajavarothayam Sampanthan, who heads the main ethnic Tamil political party.

Since coming to power in January elections, Sirisena has begun delivering on his pledges to reduce some of the powers of the president, effectively reversing changes brought in by Rajapakse to strengthen his hand.

Lawmakers voted overwhelmingly on Tuesday in favour of restoring a two-term limit for the president and reviving independent bodies to manage key institutions such as the police and the judiciary.

Kerry also praised the new government for "working on creating an enduring peace" with the Tamil minority after the end of a 37-year ethnic conflict that claimed more than 100,000 lives.

Sirisena, who mopped up most of the votes among the Tamil minority in the polls, has vowed to pursue reconciliation efforts more vigorously than Rajapakse, who had a reputation as a hardline Sinhalese nationalist.

Kerry will also discuss US interest in expanding trade and investment with Sri Lanka, a senior State Department official said. Sri Lanka exports roughly US$2.5 billion (S$3.33 billion) in goods, mostly textiles, to the United States a year.

The State Department official said Washington was "encouraged" by the new government's cooperation with the United Nations over a UN report on possible atrocities committed during the final stages of the civil war.

The United Nations said Rajapaksa's government had failed to properly investigate war crimes. In February, at the request of Sirisena's government, the UN Human Rights Council agreed to delay the release of the UN report until September.

Sirisena appears to be more willing to work with the United Nations and his government has said it wants to conduct the war crimes investigation with UN assistance.

"It's a real opening in terms of Sri Lanka's relations with the international community and with the United Nations," the State Department official said. "We'll have to see where this goes with Sri Lanka and its dialogue with the UN."