At least 16 Sri Lankan mercenaries have been killed fighting in the war between Russia and Ukraine, the island's deputy defence minister said Wednesday.

Tens of thousands of Russian soldiers have been killed in Ukraine since the invasion began more than two years ago, and Moscow has been on a global quest for more troops.

Soldiers from Sri Lanka's regional neighbours India and Nepal have also signed up to fight since last year, with several confirmed deaths in combat from citizens of both countries.

Sri Lanka opened an inquiry last week into the recruitment of its citizens for the conflict that has since identified the participation of 288 retired soldiers from the island nation, deputy defence minister Pramitha Tennakoon said.

"We have confirmed information about 16 who have been killed," he told reporters in Colombo.

Tennakoon did not say which side of the conflict the soldiers had been fighting on.

But ruling party lawmaker Gamini Waleboda told parliament on Monday that most had been recruited to fight alongside the Russian army.

Those who joined had been duped with promises of high salaries and falsely told they would be given non-combat roles, Waleboda said.

Tennakoon said the recruitment of Sri Lankans was being treated as a human trafficking enterprise and urged military officers not to fall prey to the recruitment drive.

The Sri Lankan government was also in talks with both the Ukrainian and Russian foreign ministries to track down Sri Lankans in the two countries and bring them back safely.

"This is a delicate issue," Tennakoon said. "We are friends with Russia, we are friends with Ukraine. Both are important for us so we are talking to the foreign ministries to get our people back safely."

- Police arrests -

Complaints began pouring in from relatives after the defence ministry established its probe last week to collect information on those who had travelled to both countries to join the war effort.

Sri Lanka has repeatedly warned its citizens against travelling to Russia or Ukraine to join the fighting.

But there are no restrictions on Sri Lankans travelling abroad and large numbers have left in the wake of an unprecedented economic crisis in mid-2022.

Police arrested two retired army officers, including a major general, last week for illegally acting as recruiting agents for Russian mercenary firms.

India and Nepal have also confirmed that numerous citizens of those countries had been recruited to fight alongside the Russian army over the past year.

At least 19 Nepalis had been killed in combat, according to figures from the Himalayan republic published in March.

Russia's army held off a much-hyped Ukrainian counter-offensive last year and it has since made gains as Kyiv struggles with ammunition and manpower shortages.