COLOMBO, Sri Lanka (AP) _ A strike order by Tamil separatist guerrillas crippled government operations in four northern and eastern districts Monday after the rebels threatened to kill those reporting for work, residents said.

The residents, speaking on condition of anonymity, said courts, banks, post offices and government departments did not function in the districts of Vavuniya, Batticaloa, Mannar and Jaffna.

The major rebel group, the Liberation Tigers of Tamil Eelam, threatened that anyone who reported for work would be treated as a med at ending the four-year Tamil separatist war.

Tamil rebels have been waging a guerrilla war for a separate homeland in the north and east since 1983, claiming their community is discriminated against by the majority Sinhalese on this island ont Junius R. Jayewardene.

De Mel announced the resignation at his residence in Colombo but gave no reasons.

''I have no regrets or bitterness with anyone,'' he said in a statement Monday. ''I am now at peace with all. Peace and elections, elections and peace - the only salvation for this country.

''I have made it very clear to the government and President Jayewardene that I am totally against people who believe they can solve political problems militarily,'' he said.

The 62-year-old De Mel has been a staunch supporter of the India-sponsored peace accord. But he told Parliament on Dec. 23 that a chief cause of Sri Lanka's problems has been the failure to conduct elections on time.

The last parliamentary elections were held in 1977 and the present Parliament's term was increased by six years in a 1982 referendum.

Jayewardene had attempted to forcefully put down the Tamil rebels before the July 29 peace accord. India sponsored the accord because of the sympathies of its own 60 million Tamils to the rebel cause.

More than 25,000 Indian soldiers have been battling rebels since October, when the Tigers renounced the peace plan and went on a rampage, killing more than 200 Sinhalese.

Jaywardene also faces problems from hardline Sinhalese who say the accord has granted too many concessions to the Tamils.