KABUL, Afghanistan — The Taliban struck Thursday in Afghanistan's northern province of Kunduz, leaving 15 soldiers dead there, and in western Farah province, where they killed four policemen, officials said.

In Kunduz, Taliban fighters tried to overrun a military security post in the district of Dasht-e-Arch, using artillery shells, according to army spokesman Mohammad Hanif Rezaie, who is based in Balkh province.

Along with the 15 killed, at least 13 soldiers were wounded in the four-hour-long gunbattle, he added. Rezaie also said that at least six Taliban fighters were killed, their bodies left lying on the site.

However, Mohammad Yosuf Ayubi, the head of the provincial council, said as many as 30 soldiers were killed. The disparate death tolls could not be immediately reconciled.

Later, Rezaie said the Taliban blew up a bridge they had booby-trapped leading to the site of the gunbattle to prevent military reinforcements from reaching the scene.

In the attack in Farah, the governor's spokesman Mohammad Naser Mehri said the Taliban targeted a police checkpoint.

The Taliban have not so far claimed either attack but the insurgents have recently stepped up assaults in both provinces and elsewhere in Afghanistan.

On Wednesday, a roadside bomb struck a vehicle in Farah's Khak-e Safad district, killing five civilians, including two women and a small child. That same day, two suicide bombers stormed an education department building in eastern Nangarhar province, killing at least 10 people. Both the Taliban and an Islamic State group affiliate are active in Nangarhar.

Afghan President Ashraf Ghani has repeatedly extended calls to the Taliban for peace talks but the insurgents have rejected them outright.

NATO leaders are expected to discuss Afghanistan later Thursday at their summit in Brussels during which the alliance is expected to make a commitment to keep funding the Afghan army and its training mission.