Colombo : Government troops fought their way into some of the last Tamil rebel-held areas in a north-eastern Sri Lanka on Friday, with special focus on locating the hideout of the rebel leader Velupillai Prabhkaran, military officials said.

The officials said that unmanned aerial vehicles (UAVs), which had been capturing visual images from air, also have been used to monitor the movements of the rebels and locate the area where the rebel leader is believed to be hiding.

However, a senior military official based in the northern war front told reporters on Friday that the rebel leader may have escaped in a submarine from the narrow land strip where the rebels have been cornered.

But Brigadier Shavindra de Silva, who has been leading the troops in the operations, told a group of journalist who are on conducted tour to the areas captured by the military that according to intelligence reports the rebel leader and a few of his senior members are still in the area.

Rebels are now confined to an area of eight square kilometres in Mullaitivu district, 395 kilometres north-east of the capital.

He said in the last two days of fighting 15 soldiers were killed and 75 others injured.

The number of civilians leaving the rebel-held areas has reduced since Thursday with fresh fighting reported in the area.

On Thursday only 2,934 civilians were left the rebel-held area while on Friday only 300 persons were left the area, according to the military.

A mass exodus was reported from Monday to Wednesday, when nearly 175,000 civilians fled into the government-controlled area.

Local and international organisations have expressed concern about the plight of the civilians who remain in the area. Government officials quoting civilians coming out of the area say the figure may be around 15,000 to 20,000, but other sources say the figure could be around 40,000.

Verification of the wildly differing estimates could not be obtained because of tight restrictions on news reporting in the area.

Earlier the government was maintaining that there were only 70,000 civilians trapped, but with the mass exodus it was revealed that the government estimates were inaccurate.

Meanwhile, United Nations Secretary General Ban Ki-Moon on Thursday said he was concerned about the situation in Sri Lanka and was sending a humanitarian team to the north-eastern coast where the civilians are trapped.

However, it was unlikely that such a visit would be possible as fighting continues between Tamil rebels and government troops in the area.

The military says they are on the final phase of a 25-year military campaign by the rebels to establish a separate state in the north and eastern parts of Sri Lanka. (dpa)