COLOMBO, SRI LANKA, OCT. 19 -- A group of leading citizens in the besieged northern city of Jaffna have called on Sri Lankan President Junius Jayewardene to press India to halt its "indiscriminate bombings" of the city, where they said almost 700 civilians are believed to have died.

India has consistently denied using heavy artillery or aircraft in its 10-day-old drive against Jaffna to suppress local Tamil separatists.

The appeal to the president from 12 leading Jaffna citizens contradicted Indian claims that its troops were exercising restraint during their offensive. Among the signers of the appeal were the local Red Cross representative and the administrator of Jaffna hospital.

The message was disclosed here by Tamil sources as Sri Lankan authorities announced that 40 Tamil refugees from Jaffna and an Indian military escort officer had been killed when the bus they were riding to a refugee center in eastern Sri Lanka hit a mine outside the town of Kalkudah.

Meanwhile, an Indian government spokesman in New Delhi claimed tonight that one of the four Indian columns that has been advancing on Jaffna to suppress armed Tamil militants holed up in the city had succeeded in linking up with the Indian military perimeter around the old Jaffna Fort, at the southwestern waterfront of the city.

The Indian advance would leave only about a mile of waterfront in the hands of the guerrillas of the Liberation Tigers of Tamil Eelam. This dominant Tamil secessionist organization has refused to surrender its arms to the Indians under the terms of a July 29 agreement between President Jayewardene and Indian Prime Minister Rajiv Gandhi.

The agreement has opened the door for what has become an Indian military occupation of the northern and eastern parts of Sri Lanka, with a force said to number more than 20,000 troops. The accord was meant to end a four-year civil war between the Tamil minority and Sinhalese majority.