KABUL/ISLAMABAD — Clashes have intensified between Pakistan and Afghanistan with both sides trading blows, officials from both countries said on Friday, as Pakistan's defense minister declared an "open war".

Security sources in Pakistan said they carried out airstrikes on Friday targeting Afghan military offices and posts in Kabul, Kandahar and Paktia as well as ground attacks at multiple locations along the two countries' shared border.

The Taliban said it launched attacks on Pakistani military installations in retaliation. It also called for the two sides to resolve the conflict through dialogue on Friday.

Khawaja Muhammad Asif, Pakistani defense minister, said earlier on Friday, "Our cup of patience has overflowed. Now it is open war between us and you (Afghanistan)."

Strikes on military installations are a major escalation and threaten a protracted conflict along the frontier.

Afghan spokesman Zabihullah Mujahid confirmed Pakistani forces carried out airstrikes in parts of Kabul, Kandahar and Paktia but did not give details.

Video shared by Pakistani security officials showed flashes of light in the night from firing along the border and the sound of heavy artillery. A video of strikes on Kabul showed thick plumes of black smoke rising from two sites and a massive blaze in part of the capital.

"Pakistani counterstrikes against targets in Afghanistan continue," a Pakistani government spokesman, Mosharraf Zaidi, said in a post on X, describing the action as a response to "unprovoked Afghan attacks".

Both sides reported heavy losses, issuing sharply differing figures.

Pakistan's military spokesman Ahmed Sharif Chaudhry told reporters that at least 12 Pakistani soldiers were killed and 274 Taliban officials and militants were killed since Thursday night.

Mujahid, the Taliban spokesman, said 55 Pakistani soldiers were killed and 19 posts seized, while eight Taliban fighters were killed, 11 wounded and 13 civilians injured in Nangarhar Province.

United Nations Secretary-General Antonio Guterres is following with concern cross-border clashes between Afghanistan and Pakistan, his spokesman said on Thursday.

In a note to correspondents, spokesman Stephane Dujarric said the secretary-general urges relevant parties to comply with their obligations under international law and to ensure the protection of civilians.

"Commending mediation efforts by several member states in recent months, the secretary-general urges the parties to continue to seek to resolve any differences through diplomacy," Dujarric said.

Russia called on Afghanistan and Pakistan to halt cross-border attacks immediately and resolve their differences through diplomatic means, the RIA news agency reported on Friday, citing the foreign ministry.

In Beijing, Chinese Foreign Ministry spokeswoman Mao Ning said on Friday that China has been mediating and facilitating dialogue between Islamabad and Kabul through its own channels following fresh clashes along the Afghan-Pakistani border.

Speaking at a regular news briefing, Mao said China is closely following the developments of the situation and stands ready to continue playing a constructive role in easing tensions and improving relations between the two countries.

The spokeswoman said China supports combating all forms of terrorism and called on both sides to remain calm and exercise restraint, properly resolve their differences through dialogue and consultation, achieve a ceasefire as soon as possible and avoid further bloodshed.

"Pakistan and Afghanistan are neighbors that cannot be moved away, and both are also China's neighbors. As a neighboring country and friend, China is deeply concerned about the escalation of the conflict and deeply saddened by the casualties it has caused," Mao said.

According to the spokeswoman, the Chinese Foreign Ministry and the Chinese embassies in Pakistan and Afghanistan are in communication with the relevant parties in both countries.

Relations between Kabul and Islamabad have been strained by a long-running dispute over Pakistan's accusation that Afghanistan harbors militants carrying out attacks across the border. Afghanistan has denied the charge and said Pakistan's security is an internal problem.

Clashes between Pakistan and Afghanistan in October killed dozens of soldiers until negotiations facilitated by Turkiye, Qatar and Saudi Arabia brought an end to the hostilities.

Pakistan and Saudi Arabia's foreign ministers spoke on Friday to discuss reducing tensions, Riyadh's foreign office said without providing details on whether Riyadh was involved in brokering a ceasefire.

Mo Jingxi in Beijing contributed to this story.

Agencies - Xinhua