An Afghan government negotiator on Thursday said the Taliban had offered a three-month ceasefire in exchange for the release of 7,000 insurgent prisoners, as the militant group continues a sweeping offensive across the country.

“It is a big demand,” Nader Nadery said, adding that the insurgents have also demanded the removal of the Taliban’s leaders from a United Nations blacklist.

The announcement came as Pakistan guards used tear gas Thursday to disperse hundreds of people who tried to breach a border crossing into Afghanistan, officials said.

The frontier was closed a day earlier by Pakistan after the Taliban seized the Afghan side in Spin Boldak district, continuing sweeping gains made by the militants since foreign forces stepped up their withdrawal from Afghanistan.

“An unruly mob of about 400 people tried to cross the gate forcefully. They threw stones, which forced us to use tear gas,” said a security official at the southwest Chaman border on the Pakistan side, who asked not to be named.

He said around 1,500 people had gathered at the border, waiting to cross since Wednesday.

“We had to baton charge because people were getting unruly,” said a second border official, who also did not want to be named.

Jumadad Khan, a senior government official in Chaman, said the situation was now “under control”.

An Afghan Taliban source told AFP that hundreds of people had also gathered on the Afghan side, hoping to get into Pakistan.

“We are talking to Pakistani authorities. A formal meeting to open the border is scheduled for today, and hopefully, it will open in a day or two,” he said.

The crossing provides direct access to Pakistan’s Balochistan province — where the Taliban’s top leadership has been based for decades — along with an unknown number of reserve fighters who regularly enter Afghanistan to help bolster their ranks.

A major highway leading from the border connects to Pakistan’s commercial capital Karachi and its sprawling port on the Arabian Sea, which is considered a linchpin for Afghanistan’s billion-dollar heroin trade that has provided a crucial source of revenue for the Taliban’s war chest over the years.

Spin Boldak was the latest in a string of border crossings and dry ports seized by the insurgents in recent weeks as they look to choke off revenues much-needed by Kabul while also filling their own coffers.

Afghanistan’s interior ministry has denied the Taliban have taken the area even as social media was flooded with pictures of insurgent fighters relaxing in the frontier town.

Hours after the crossing fell, an AFP reporter on the Pakistani side saw around 150 Taliban fighters riding on motorcycles, waving insurgent flags and demanding to be allowed to cross into Afghanistan.