Kabul: Some 20,000 people from Pakistan's northwestern tribal region of Bajaur have fled to Afghanistan this summer due to intense fighting between government forces and militants, the United Nations said on Sunday.

Key region

The Pakistani military launched an offensive in August for control over the strategically key region of Bajaur and have been involved in heavy fighting since then.

"More than 3,900 families, or around 20,000 individuals, have fled fighting in Bajaur ... into Kunar province in eastern Afghanistan," said the United Nations High Commission for Refugees in Afghanistan.

"In the last two weeks alone, over 600 Pakistani families have fled into Afghanistan," it said.

Bajaur is the smallest of Pakistan's seven so-called tribal agencies, semi-autonomous ethnic Pashtun regions along the Afghan border, with a population of one million people.