Sri Lanka's government has reinstated a ban on the Tamil Tiger rebels, as government troops push further into the separatists' last northern strongholds.

Officials say the Cabinet banned the rebels Wednesday because, they say, the separatists are not allowing civilians to leave the war zone.

Sri Lankan Air Force aircraft prepare for take off at an airbase on the outskirts of Colombo, 02 Jan 2009

Their claim could not be independently verified because Sri Lanka's government bars journalists from conflict areas. However, international rights groups also have accused the rebels of holding civilians as human shields. The rebels deny the accusations.

The government lifted its ban on the rebel group in 2002 as part of a truce brokered by Norway. Colombo officially abandoned the truce last year, after both sides violated the accord repeatedly.

The Defense Ministry said Wednesday that soldiers are closing in on the rebels' key land routes in the Jaffna Peninsula and the strategic Elephant Pass.

They captured the rebels' administrative capital, Kilinochchi, last week.

The Tamil fighters are vowing to hit back. One of their leaders, B. Nadesan, says on a pro-rebel Web site (TamilNet) that the group is determined to "overcome the current challenges."

The 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.