KABUL: An Afghan official says insurgents are arriving in huge numbers from neighboring Pakistan in an effort to destabilise 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.

Read: Fighting between Taliban and Afghan forces claims 30 lives

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.

— Pakistani authorities are yet to comment on the matter

US military sends jets to northern Afghan city under siege

The US military has sent fighter jets to Afghanistan's northern province of Kunduz, where Taliban insurgents have launched a major offensive and overrun government checkpoints close to the main city, US and Afghan sources said.

The US military declined to say why the jets had been dispatched to the area, but confirmed they were on a mission outside regular operations.

“We can confirm there were US jet aircraft flying in the Kunduz area in the past 72 hours, no munitions dropped,” a US military spokesman said, but declined to comment further.

Officials this week said hundreds of Taliban militants had attacked police and army checkposts in the province, the insurgents' last stronghold before US-led forces drove them from power in 2001.

Two airstrikes were conducted in the province, the interior ministry said in an internal report, including one in the city district on Monday.

The coalition combat mission in Afghanistan ended last year, and only a small contingent of around 1,800 US counter-terrorism troops are still involved in combat operations.

Last year the US military said it would no longer support Afghan security forces in routine combat operations, except “in extremis”, or in emergencies, to avoid mass casualties.