Sri Lanka's military says troops fighting are to capture the highly strategic Elephant Pass, the Tamil Tiger rebels' last stronghold in the north.

Military officials Friday said the causeway, which links the Jaffna peninsula with the northern mainland, was close to falling to government troops after they entered the area days ago. Most of the Jaffna peninsula is already in government hands.  Troops captured the rebel capital Kilinochchi, last week.

Meanwhile, authorities said at least three security personnel and four civilians were killed in northeastern Sri Lanka Friday during a rebel attack.

Officials say a vehicle was hit by a roadside bomb set up near the city of Trincomalee. Authorities say the bomb exploded as security personnel escorted a convoy through the area. 

The rebels have dismissed the army's recent gains as "insignificant" and have vowed to continue fighting the government.

The Tamil Tiger rebels have been fighting since 1983 to establish an independent homeland for members of the Tamil ethnic minority in the island nation's north and east.  They say Tamils are treated as second-class citizens by the Sinhalese majority.  The civil war has killed more than 70,000 people.

The United States considers the Tamil Tigers a terrorist organization but is calling for a peaceful dialogue to resolve what it calls the "legitimate issues of the Tamils." 

Some information for this report was provided by AFP, AP and Reuters.