Five members of Afghan security forces were killed in a bombing targeting their base, officials said Monday, just days after the US military warned the Taliban against unleashing violence.

The truck bomb attack late on Sunday, claimed by the insurgents, was the first of its kind since they signed a deal with the US in February meant to help bring peace to the country.

The group targeted a joint base used by the Afghan army and the country's intelligence agency in the southern Afghan province of Helmand.

Five members of the security forces were killed and seven wounded, Omar Zwak, spokesman for Helmand's governor, told AFP.

An Afghan army officer also confirmed the attack. "We have five dead, all members of the intelligence agency," Enayatullah Abed said, adding that eight others were also wounded in the bombing. "It was a truck bomb carried out against the base. Half of the base has been destroyed in the attack."

On Saturday, the US military in Afghanistan issued a warning to the Taliban. "If the violence cannot be reduced then yes, there will be responses", US Forces-Afghanistan spokesman Colonel Sonny Leggett wrote in a letter to Taliban spokesman Zabihullah Mujahid.

Under the terms of the US-Taliban deal, the insurgents committed to stop striking US and foreign partner troops and agreed to start peace talks with the Kabul administration, in return for the withdrawal of foreign troops.

While the Taliban have refrained from hitting coalition forces and cities, they returned to the battlefield the moment the deal was signed and have been unleashing an average of 55 attacks a day on Afghan forces, according to Afghan officials.

US President Donald Trump has repeatedly said he wants American troops home, and the Taliban realise that as long as they do not hit American or foreign troops, there are few consequences for continued attacks, experts say.