NATO chief Jens Stoltenberg on Sunday hailed a power-sharing deal struck between Afghanistan's political rivals and urged them to work in unison towards lasting peace.

The agreement was signed by President Ashraf Ghani and his rival Abdullah Abdullah to end a bitter rivalry that plunged the country into a months-long political crisis.

"I welcome the decision taken by Afghanistan's political leaders to resolve their differences and join efforts to form an inclusive government," Stoltenberg said in a statement.

The deal comes as Afghanistan battles the COVID-19 pandemic and surging militant violence that saw dozens killed in brutal attacks last week.

"In the midst of the COVID-19 pandemic and continued Taliban violence against their fellow Afghans, it is more important than ever that all Afghan leaders unite and work towards enduring peace in Afghanistan," Stoltenberg said.

"All parties should seize this unprecedented opportunity for peace."

Under the agreement, Abdullah will lead future peace talks with the Taliban, who have already signed a landmark accord with Washington to pave the way for the withdrawal of foreign forces, including NATO's training mission, from Afghanistan.

NATO ended combat operations in the country at the end of 2014, but still has a 16-000-strong mission to train, advise and support local forces.