Sri Lanka's former Army chief and defeated presidential candidate Sarath Fonseka has been arrested, his family told reporters on Monday.

Fonseka was arrested by the military police, sources said.

The local English newspaper Daily Mirror reported on its online edition that Fonseka's media secretary Senaka de Silva was also arrested.

Weekend newspapers had speculated that Fonseka would be arrested and hauled before a military court for several allegations including an assassination attempt against Sri Lankan President Mahinda Rajapaksa.

He was the main challenger to Rajapaksa in the island's sixth presidential election held on Jan. 26, in which he was defeated by Rajapakesa by a large majority of 1.8 million votes.

Fonseka was a key figure in the government's military offensive against Tamil Tiger rebels from 2006 to 2009. However, he resigned from the military in November 2009 and ran for the presidency as the common candidate of the opposition parties.