KANDAHAR - Taliban fighters killed 30 soldiers in an attack on an army base in the southern province of Kandahar, an army spokesman said on Wednesday, as heavy fighting raged across the country.

Sediq Esa, spokesman for the 205th Corps in Kandahar, said the Taliban attacked an outpost in Khakriz district, to the north of Kandahar city, overnight, seizing the outpost and capturing weapons and vehicles.

"As a result of the fighting, 30 army personnel have been killed and others wounded," he said.

However the 205th Corps commander, Gen Imam Nazar, disputed the death toll and said reinforcements had arrived to beat back the insurgents.

The attack came after days of fierce fighting across Afghanistan and underlined the steadily deteriorating security in much of the country, which has also seen a string of high profile attacks in cities including the capital Kabul.

While the fighting has intensified, the United States, which is expected to send around another 4,000 troops to Afghanistan to bolster its existing training mission, is still to announce its new strategy for the region.

The Taliban, fighting to restore Islamic rule to Afghanistan 16 years after being driven from power by a US-led campaign, controls or contests at least 40 percent of the country, inflicting what US advisers say are unsustainable casualties on Afghan security forces. In the first 10 months of last year alone, some 6,785 soldiers and police were killed.

On Wednesday, the Taliban's main spokesman said the insurgents were close to taking Waygal district in the eastern province of Nuristan, a day after they took Jani Kheil district in Paktika province, further to the south.

Over the past week, the insurgents have also taken districts in Ghor province in the west and Faryab in the north, although the defense ministry said government forces had retaken Kohistan district in Faryab.

Kunduz, the northern city which the Taliban captured briefly in 2015 and managed to enter in 2016, has also been under heavy pressure.

US advisers say that Afghan security forces, fighting largely alone since a NATO-led coalition ended its main combat mission in 2014, have made progress but still rely too much on vulnerable checkpoints exposed to Taliban attack.

AFP adds: The Afghan air force said it carried out strikes backing up soldiers on the ground during the hours-long attack on the base, which began late Tuesday and ended in the early hours of Wednesday.

At least 13 soldiers were also wounded in the attack, MOD spokesman General Dawlat Waziri said. The Afghan forces "bravely resisted", he added, killing more than 80 insurgents.

The camp was located in the remote Karzali area of Khakrez district, near the border with restive Helmand, where the Taliban hold vast swathes of territory.

"We conducted multiple airstrikes killing dozens of them. Our helicopters transported wounded soldiers to hospitals in Kandahar," said General Raziq Shirzai, the provincial air force commander.

One senior army source said up to 12 soldiers are still missing following the assault, which he described as a "very heavy attack". The insurgents stole guns and vehicles as they retreated, he said.

Residents described hearing the airstrikes, and said the attack was launched by a 30-strong convoy carrying "hundreds" of Taliban who assaulted the base from multiple directions.

The insurgents claimed the attack via their Twitter account.

Afghan security forces - beset by a high death toll, desertions and non-existent "ghost soldiers" on the payroll - have been struggling to beat back the insurgents since US-led NATO troops ended their combat mission in December 2014. Casualties among Afghan security forces soared by 35 percent in 2016, with 6,800 soldiers and police killed, according to US watchdog SIGAR.