Japanese Prime Minister Shinzo Abe said he hoped Sri Lanka's war crimes probe would silence its critics ahead of his arrival Sunday on the island to push for stronger trade ties.
Abe told the local Sunday Times newspaper he also hoped Sri Lanka could achieve "true national reconciliation" five years after the military crushed ethnic Tamil rebels to end the island's separatist war.
Sri Lanka has been under intense international pressure over war crimes allegedly committed by the military in the final months of the war.
The UN rights body in March ordered an international panel to investigate charges that Sri Lanka's security forces killed at least 40,000 Tamil civilians.
Abe noted that Colombo, which has refused to cooperate with the UN-mandated probe, had expanded the mandate of its own inquiry into those disappearances during the war to include investigating war crimes claims.
"Japan hopes such efforts made by Sri Lanka will lead to dispel concerns indicated in the resolution by the UN Human Rights Council," Abe said in an interview with the newspaper published Sunday.
Japan, the largest single foreign aid donor to Sri Lanka, remained neutral at the UN Human Rights Council vote in March that voted to set up the war crimes probe.
Abe arrives from Bangladesh later Sunday as part of a regional tour aimed at boosting trade and offsetting China's mounting influence in South Asia.
Abe, who is travelling to Colombo with a business delegation, will be the first Japanese premier in 24 years to visit the Indian Ocean island.
He is due to hold talks with President Mahinda Rajapakse on expanding their economic and political ties, Sri Lanka's information minister said.
Officials said Japan was helping Sri Lanka set up a new digital television broadcast system and was also assisting with upgrading the transport sector.
Abe and Rajapakse also aim to strengthen maritime territorial cooperation in the face of a more territorially assertive China, media reports said.
On Saturday, Abe won Dhaka's support for Tokyo's bid for a non-permanent seat on the UN Security Council.
Bangladeshi Prime Minister Sheikh Hasina said Dhaka would withdraw its candidacy in favour of Tokyo in view of Japan's "continued and strong support in Bangladesh's development process".
Abe's tour follows Indian Prime Minister Narendra Modi's trip to Tokyo this month during which the two countries, which both have prickly relations with giant neighbour China, declared they would raise ties to a "new level".