Sri Lanka is investigating its former ambassador to Russia following a media report that he helped arm pro-Moscow separatists in Ukraine, the foreign minister said Sunday.

The Colombo-based Sunday Times said the Ukraine government has lodged a formal complaint with Colombo detailing former ambassador Udayanga Weeratunga's alleged arms dealings with the rebels.

"We will conduct a full investigation into this matter," Foreign Minister Mangala Samaraweera told the newspaper.

Samaraweera confirmed his comments in a text message to AFP but did not give details. The government recalled Weeratunga soon after President Maithripala Sirisena came to power in January elections.

Weeratunga, a close relative of defeated former long-time president Mahinda Rajapakse, operated a restaurant in the Ukrainian capital Kiev before he was appointed Sri Lanka's ambassador to Moscow nine years ago, the paper added.

Weeratunga has not spoken about the allegations and could not be contacted on Sunday for comment.

The Sunday Times did not give details of Weeratunga's alleged involvement in weapons sales.

A shaky truce is in force in the conflict in Ukraine's rebel-held east which has claimed more than 6,000 lives in 11 months.

Kiev and the West accuse Russian President Vladimir Putin of supporting the insurgency with troops, tanks and heavy weapons -- accusations he denies.

Ex-army chief becomes Sri Lanka's first field marshal
Colombo (AFP) March 22, 2015 - Sri Lanka's new government Sunday conferred the highest military rank of field marshal on retired army chief Sarath Fonseka, who had been jailed for alleged treason by the previous regime.

President Maithripala Sirisena awarded Fonseka the title at a state ceremony in the capital and said he was unjustly treated by the previous government.

Fonseka was thrown in jail after he unsuccessfully tried to challenge a re-election bid by the then-strongman president Mahinda Rajapakse in 2010.

Soon after he toppled Rajapaksein a January election, Sirisena used his executive powers to clear Fonseka of all the allegations, including treason and dabbling in politics while in uniform.

Ensuring justice for Fonseka was a "responsibility undertaken by the (new) government in our quest for justice for the whole of the army", Sirisena said.

Fonseka led troops to victory over the separatist Tamil Tiger rebels in 2009, but then fell out with Rajapakse over who deserved the credit.

The decorated general was publicly humiliated and stripped of his rank, pension and medals collected in a 40-year career. He spent two years in jail and lost the right to contest elections for seven years.

The United States considered Fonseka a political prisoner and campaigned for his unconditional release, which eventually came in May 2012.

The new president, who was backed by Fonseka in the run-up to the January 8 election, granted a pardon and completely exonerated him of previous convictions as well as pending charges of treason.

Soon after his 2010 poll defeat, Fonseka was detained on a charge of corruption relating to military procurements and then given a 30-month jail sentence.

In November 2011 he was sentenced to three more years in jail for saying that Tiger rebels who surrendered had been killed on the orders of Rajapakse's brother Gotabhaya Rajapakse, the then-defence secretary.

Fonseka had also angered the government by saying he would testify before any international tribunal probing possible war crimes charges.

Sri Lanka's former government had denied any civilians were killed by its troops at the climax of the 37-year war in 2009, which is believed to have left up to 100,000 people dead.