Article published on the 2009-11-12 Latest update 2009-11-12 14:31 TU
Fonseka is thought to have clashed with the president and his brother over who was responsible for the victory over the rebels which ended the country's 37-year-old conflict.
The military campaign was dogged by allegations of serious human rights abuses. The United Nations says as many as 7,000 civilians may have died in the fighting this year. The government claims that no civilians were killed by its troops.
Following the victory, Fonseka was named chief of defence staff. The position is seen as a ceremonial one that has no command responsibility. The government has warned that serving officers will be prosecuted if they enter politics while in uniform.
The main opposition has hinted that the general, a popular, Sinhalese nationalist, will be their common candidate to challenge the incumbent president.
The general visited a Buddhist temple just outside Colombo on Thursday to seek the blessings of the monks after his resignation.
Sri Lanka