Colombo, Jun 30 (IANS): Former Sri Lankan Army Chief Sarath Fonseka, who led the final stages of the war that crushed the Tamil Tigers, on Thursday joined the ruling United National Party (UNP).

Fonseka obtained the party membership from party leader and Prime Minister Ranil Wickremesighe, a UNP spokesman said.

The former army commander contested last year's parliamentary elections but failed to garner enough votes, Xinhua news agency reported. In February he was given a vacant seat in the parliament.

The decision was taken when the UNP Working Committee met to decide on the seat left vacant following the demise of another legislator.

Fonseka's Democratic Party and the ruling UNP then reached an agreement to work together. He was also made a minister in the government.

The move drew angry reactions from Tamil political parties and human rights groups.

Fonseka has been accused by human rights groups of involvement in war crimes during the final stages of the civil war.

He led the army during the final battle against Tamil Tiger rebels, which eventually led to their defeat in May 2009 after 30 years of war.