Flash floods triggered by heavy rain have killed at least 14 people and destroyed dozens of houses in northern Pakistan, officials said on Thursday.

Irshad Bhatti, a spokesman for the country's National Disaster Management Authority said the death toll may rise as survey teams have reported more deaths but are still assessing the extent of damages.

Most of the deaths were reported in the northwestern province of Khyber Pakhtunkhwa, where nine people died and more than 50 houses were destroyed. In Pakistan-administered Kashmir, six people were killed after a roof collapsed.

"The death toll may rise, we are assessing the damages. Rescue work is continuing and relief activities have started," Bhatti said.

Floods in Pakistan in the summer of 2011 affected 5.8 million people, with floodwaters killing livestock, destroying crops, homes and infrastructure as the nation struggled to recover from record inundations the previous year.