Image copyright Reuters Image caption Security forces are coming under pressure from Taliban in the Kunduz area

More than 2,000 families have been forced to flee their homes in the northern Afghan city of Kunduz amid heavy fighting, officials say.

The evacuations came as Taliban militants seized the district of Qala-e-Zal, just west of the city.

Clashes continue in other parts of the city, as the Taliban try to increase pressure on government troops in both the north and south of the country.

The militants twice entered Kunduz in the past two years before retreating.

BBC South Asia editor Jill McGivering says this is a classic example of surge and retreat which is now common in Afghanistan as the Taliban tries to extend its reach but struggles to retain new ground.

The Norwegian Refugee Council (NRC) said in a statement that while some fleeing families were able to find refuge with relatives others were forced to sleep in the open.

"Those with no money, like widows, are in Qala-e Zal desert, as they couldn't make it as far as the city. They are now living in the open," local resident Abdul Karim told the NRC.

A recent US report suggests more than 600,000 Afghans were displaced by fighting last year, a 40% increase on the previous year.

There has been increased fighting in northern Afghanistan since the Taliban announced their Spring offensive on 28 April.