Germany had the second largest military contingent in Afghanistan after the United States, losing more troops in combat in Kunduz than anywhere else since World War Two.

The Taliban overran three provincial capitals including Kunduz at the weekend as it pressed an offensive since foreign troops began a withdrawal.

"The reports from Kunduz and from all over Afghanistan are bitter and hurt a lot," Defence Minister Annegret Kramp-Karrenbauer said on Twitter.

"Are society and parliament prepared to send the armed forces into a war and remain there with lots of troops for at least a generation? If we are not, then the joint withdrawal with the partners remains the right decision."

Some within her own conservative party want German troops to participate in an intervention against the Taliban, but Kramp-Karrenbauer said defeating them would require a long and hard campaign.

Since the United States announced plans in April to pull out troops by Sept. 11, and the transatlantic alliance NATO followed suit, violence has escalated as the Taliban seize territory.

Kramp-Karrenbauer blamed former U.S. President Donald Trump for undermining the Afghanistan operation, even though it is his successor Joe Biden implementing the withdrawal policy.

"Trump's unfortunate deal with the Taliban was the beginning of the end," she said of an agreement Trump struck with the Islamist militants in 2020 for U.S. troops to leave.