An Afghan official says insurgents are arriving in huge numbers from neighboring Pakistan in an effort to destabilize Afghanistan's northern provinces.

Interior Ministry spokesman Sediq Sediqqi said Wednesday that Afghan troops are engaged in fierce fighting outside the provincial capital of Kunduz, where the Taliban launched an attack last week as part of their annual spring offensive.

Sediqqi says the Taliban are being joined by "terrorists" arriving from Pakistan, who include foreign fighters from neighboring countries.

He says around 200 militants have been killed so far, along with 12 Afghan soldiers in fighting in Kunduz province.

Pakistan launched an operation against militants in its region of North Waziristan, bordering Afghanistan, in mid-2014. The Pakistani operation has driven many anti-government fighters over the border into Afghanistan.