Pakistani troops and Taliban militants are engaged in fierce battles on the streets of towns in northwestern Pakistan's Swat Valley.

The military say troops are fighting militants in Matta and Kanju, and soldiers are advancing toward Swat's main city of Mingora.

The United Nations says about 1.5 million people have been displaced by fighting in northwestern Pakistan this month alone.

A spokesman for the U.N. refugee agency, Ron Redmond, said he has not seen a displacement crisis grow "so big and so fast in years." The agency also says rising temperatures and a lack of shade are posing additional challenges.

A Pakistani woman from Dir who is seeking refuge in a camp for displaced people told VOA's Radio Deewa that they do not have regular supplies of water and food. And a schoolgirl lamented that she had no way to carry on her education.

There has been no official announcement about civilian casualties, but the military announced Tuesday that 16 militants and four soldiers were killed in the latest fighting. Military officials say 1,000 militants have been killed since the offensive began.

A Pakistani interior ministry spokesman emphasized that the military has been ordered to avoid harming civilians.

Human Rights Watch has accused the Taliban of endangering civilians in Mingora by using them as human shields and planting landmines throughout the town. The rights group also said Pakistani forces need to do more to prevent loss of civilian life.

Also Tuesday, Prime Minister Yousuf Raza Gilani addressed a conference of religious scholars and leaders. He defended the government's decision to fight Taliban militants, and he condemned them for targeting places of worship and accusing the government of being "un-Islamic."