A prolonged attack on a major Afghan army base that was handed over by NATO forces last month has left at least eight Afghan soldiers dead and seven more injured as a separate attack in Sangin killed at least five.

Up to 26 Taliban fighters have also been killed in the attack on Shorabak, formerly Camp Bastion, which began overnight on Friday and was continuing the next morning, government officials said on Saturday.

Al Jazeera's Charles Stratford, who is in capital Kabul, also reported an explosion and an ongoing gunfire near the Afghan parliament. 

Meanwhile, in Helmand provincial, government official confirmed that the battle was going on, our correspondent reported.

"We have spoken to an official who says this attack is ongoing. At least 26 Taliban fighters have been killed, six of whom detonated their suicide vests," he said.

Eight Afghan National Army (ANA) soldiers have been killed and many more wounded, our correspondent said.

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"The Taliban has vowed to continue to step up their attacks on both foreign targets and the Afghan National Security Forces (ANSF) in the wake of the approval of the security agreement."

Under the agreement, recently approved by Afghanistan's upper house, foreign troops will remain in the country to fight the Taliban and train the Afghan army.

The Afghan government's support for a continued international military presence has led to an increase in Taliban attacks, who are intensifying their war against the administration of President Ashraf Ghani.

Immediately after his September inauguration, Ghani signed bilateral security agreements with the US and NATO, and he has made clear his intention bring peace to Afghanistan, which has been at war for the past 30 years.

Attacks across nation

Kabul has seen almost daily attacks in recent weeks, with Taliban fighters turning their focus to high-profile foreign targets as well as ANSF.

Also on Saturday, suicide bombers attacked another military base in the Snagin district, killing five soldiers and wounding seven.

Elsewhere in Helmand, two police officers were killed and two wounded in a suicide attack on Friday on their vehicle in Nawzad district, Ahmad Obaid, a local police spokesman, said.

In the eastern Nangahar province, 31 people were wounded when a mosque was bombed during Friday prayers, according to Niamatullah Noorzai the chief of volatile Khogyani district. No one claimed responsibility for the attack.

On Thursday, a suicide attacker in a car filled with explosives struck a British embassy vehicle on a busy road in the east of Kabul, killing a British security guard and an Afghan driver.

The 13-year NATO combat mission finishes at the end of this year, to be replaced by a 12,500-personnel follow-up mission to support the Afghan army and police who are now responsible for defeating the Taliban.

NATO troop numbers in Afghanistan peaked at 130,000 in 2010, and fears are growing that the declining international presence will lead to an increase in Taliban activity.

Source: Al Jazeera and agencies