The World Food Program is being investigated in Sri Lanka for gifting luxury duty-free vehicles to a charity headed by former president Mahinda Rajapakse's wife, officials said Tuesday.

Police said an investigation into an accident involving a sports utility vehicle revealed that it was one of two SUVs to be given as a "donation" by the UN agency to Shiranthi Rajapakse's Siriliya Saviya Foundation and that neither party had paid import taxes which can be up to 350 percent.

A fleet of four-wheel drive vehicles was imported by various UN agencies in early 2005 to carry out relief and reconstruction after the December 2004 Asian tsunami which claimed at least 31,000 lives in Sri Lanka.

There was no comment from the WFP office in Colombo, but the agency's regional bureau in Bangkok said the agency had followed "standard WFP protocols and procedures" in donating the vehicles.

"It is the obligation of recipients to either to pay the duty, taxes and all the dues or seek a waiver from the government (of Sri Lanka)," WFP's Angeli Mendoza said in an e-mail response to AFP.

"The recipient officially acknowledged receipt of the donated vehicle and WFP has not received any indication from the recipient of its inability to pay for the dues," Mendoza said.

However, a spokesman for the finance ministry said it had initiated an investigation to find out how the WFP transferred ownership of the vehicles to locals without prior approval.

Foreign ministry sources said they had already asked the WFP for an explanation of their donations of vehicles imported for tsunami relief operations.

The vehicles were gifted in 2012 at a time when Rajapakse's government was at loggerheads with the UN over alleged war crimes committed by government troops while crushing Tamil separatists in 2009.

The government had also imposed restrictions on the UN and its staff travelling to the former war zone.

The WFP did not say on what basis they choose the former first lady's charity to receive the vehicles.

Shiranthi Rajapakse is already being investigated by the police Financial Crimes Investigation Division over the alleged misappropriation of funds of her foundation which helps women in rural areas.

The new government which came to power after the defeat of Rajapakse at the January 8 election has begun investigations to recover billions of dollars said to have been siphoned off during his decade in office.