By Gul Yousafzai and Asif Shahzad

Pakistan on Monday reopened a major southwestern border crossing with Afghanistan that is currently under Taliban control on the Afghan side, Pakistani customs officials said, allowing over 100 trucks carrying goods to cross into Afghanistan.

The Chaman-Spin Boldak crossing, a key port for landlocked Afghanistan, had been closed by Pakistan for commercial traffic since fierce fighting for control of the crossing erupted between Taliban insurgents and Afghan security forces earlier this month.

"Pakistan has opened its border with Afghanistan at Chaman today and resumed Afghan Transit Trade which was suspended since the last one month," Arif Kakar, a senior official of the Chaman border district, told Reuters.

He said it would remain open six days a week.

Two Pakistani customs officials, requesting anonymity, told Reuters that Spin Boldak and the border town of Wesh were still under Taliban control, and they did not know what arrangements were in place across the border or who was clearing the goods through customs.

They said Pakistani officials were under pressure by traders to let trucks pass through as the goods they were carrying would otherwise perish.

Afghanistan's interior and finance ministries, and the Taliban spokesman, did not respond to requests for comment.

U.S. Marine General Kenneth McKenzie, head of U.S. Central Command, which oversees American forces in Afghanistan, told reporters in Kabul on Sunday that Spin Boldak was a "contested space" and the Afghan government was looking to regain control of it.

The reopening came hours after 46 Afghan soldiers sought refuge in Pakistan after losing control of military positions further north along the border following advances by Taliban insurgents taking advantage of foreign forces' withdrawal.

The Afghan military commander requested refuge at the border crossing in Chitral in the north, the Pakistan army said in a statement, adding safe passage into Pakistan was given on Sunday night after clearance from Afghan authorities.

Hundreds of Afghan soldiers and civil officials have fled to neighbouring Tajikistan, Iran and Pakistan in recent weeks after Taliban offensives in border areas.

"Afghan soldiers have been provided food, shelter and necessary medical care as per established military norms," the statement said.

Relations between neighbours Afghanistan and Pakistan have taken a sharp downturn in recent weeks, particularly over repeated allegations by Kabul that Pakistan is backing the Taliban - a charge Islamabad denies.

Afghanistan recalled its diplomats from Pakistan after the brief kidnapping of the Afghan ambassador's daughter in Islamabad earlier in the month.

Afghan officials did not respond to a request for comment on the soldiers' crossing.

The Taliban has escalated its offensive since the United States announced in April that it would withdraw its troops by September, ending a 20-year foreign military presence.

Washington has said it will continue to carry out air strikes to support Afghan forces facing insurgent attacks.

Peace talks between the Afghan government and the Taliban have failed to make substantive progress since beginning in September last year.

Reeling from battlefield losses, Afghanistan's military is overhauling its war strategy to concentrate forces around critical areas such as Kabul and other cities, and border crossings.

The Pakistan army said the soldiers who sought refuge will be returned to Afghanistan after due process, as had occurred in the case of another batch of 35 soldiers earlier in July.