At least 10 Afghan soldiers were killed when militants attacked their army base in the southern province of Kandahar, the defence ministry said Tuesday, in the latest attack on Western-backed forces.

The assault in Shah Wali Kot district late Monday came just a day after 20 Afghan policemen were killed when Taliban fighters stormed their outposts in the neighbouring province of Zabul.

No group has so far claimed responsibility for the Kandahar attack, but it comes as Taliban insurgents intensify their annual spring offensive and their strength is growing, more than 15 years after they were toppled from power in a US-led invasion.

“Last night the enemies of Afghanistan attacked Achakzai camp of army corps 205 in Shah Wali Kot district,” the defence ministry said in a statement, without identifying the attackers.

“Ten brave army soldiers were martyred and nine others wounded. The wounded soldiers were taken to hospital and they are in stable condition.”

The attack marks another setback for Nato-backed Afghan forces. It comes just a month after the Taliban killed at least 135 soldiers in the northern province of Balkh in the deadliest insurgent attack on an Afghan military base since 2001.

During the Zabul attack early Sunday, local officials made desperate calls to Afghan television stations to seek attention because they were unable to contact senior authorities for help, highlighting the disarray in security ranks.

As of February only about 60 per cent of Afghanistan's 407 districts were reported to be under government control, with the authorities in Kabul struggling to counter the ascendant Taliban, according to the US watchdog agency SIGAR.

The battlefield losses have raised concerns about the capacity of Afghan forces, beset by unprecedented casualties and blamed for corruption, desertion and “ghost soldiers” who exist on the payroll but whose salaries are usurped by fraudulent commanders.

Even the fortified Afghan capital is gripped by insecurity. Gunmen stormed an international guest house late Saturday that left a German aid worker and an Afghan guard dead and a Finnish woman kidnapped.

Kabul police said they were investigating the incident as a “terrorist” attack, suggesting that the Taliban may have been behind it, but there has so far been no claim of responsibility.

The Taliban launched their annual “spring offensive” in late April, heralding a surge in fighting as the US tries to craft a new Afghan strategy.

US Defense Secretary Jim Mattis last month warned of “another tough year” for security forces in Afghanistan.

US President Donald Trump is considering sending thousands more troops to break the stalemate against the resurgent militants.

US troops in Afghanistan number about 8,400 today, and there are another 5,000 from Nato allies, who serve mainly in a training and advisory capacity.

The troop strengths are a far cry from the US presence of more than 100,000 six years ago.