Northern Lebanon was the scene of intense fighting for a third day in a row on Sunday as Lebanese troops continued to bombard al-Qaeda-linked militants barricaded in a Palestinian refugee camp near Tripoli.

"The fighting seems to have got more intense," the CBC's Nahlah Ayed reported from Beirut, where she is monitoring the fighting involving the Fatah Islam militants at the Nahr el-Bared camp.

"There are unconfirmed reports that the Lebanese army is advancing a little more into the camp than it had previously," she said.

The military said Sunday that eight soldiers have been killed in the last two days and 30 others wounded," Ayed said.

As well, at least six militants in the camp have been wounded since Friday, Fatah Islam's deputy commander Abu Hureira, a Lebanese whose real name is Shehab al-Qaddour, told the Associated Press.

One senior leader of Fatah Islam was killed on Saturday, Ayed said.

"He was apparently high up in the structure. He was a military commander," she said, adding that there are also unconfirmed reports another senior leader was either killed or badly injured.

Lebanese troops also clashed with militants at the entrance of Ain al-Hilweh, Lebanon's largest refugee camp, near the southern city of Sidon and some 42 kilometres south of Beirut. One Lebanese soldier was killed and two were injured when militants launched a grenade at a military checkpoint.

Surrender 'unthinkable'

Fatah Islam has rejected government calls for a surrender.

"This is not only impossible, this is unthinkable. Our blood is cheaper than handing over our weapons and surrendering," Abu Hureira said. 

While the fighting rages, Ayed said, it is difficult to know exactly what is happening.

"Civilians who are tucked into the camp are not able to see what is happening because they simply can't move under fire," she said.

"What few tall buildings there were in the camp that were used by militants to fire from have now been levelled."

The government of Lebanon has vowed to crush the militants, although an all-out assault on the camp would risk sparking violence elsewhere in the country.