One of the injured soldiers is airlifted to Camp Bastion after blast and gun battle in which five insurgents are killed

At least 10 British troops have been injured in a suspected suicide car bomb attack on a patrol base in Afghanistan's Helmand province. The insurgents followed up the blast with small arms fire on the base in Nad Ali, one of the districts where UK troops have been based during their time in the country.

Five insurgents were killed in the attack on the base on Monday night, which is jointly operated by the Afghan army and troops from Nato's International Security and Assistance Force (Isaf).

Though no Isaf troops died in the attack, it is understood one British soldier was severely wounded and airlifted by helicopter to Camp Bastion, the main UK base in the province. Most of the others were "walking wounded". Members of the Afghan national security force were also among the injured.

The attack is the boldest the insurgents have undertaken during the winter months – no UK soldiers have been killed here since January, making it one of the quietest tours the British have experienced since troops were deployed here in 2006.

Isaf said: "We can confirm that last night in Nad Ali district, Helmand province, insurgents attacked a combined Afghan and Isaf patrol base with a vehicle-borne improvised explosive device and small arms fire. A number of insurgents were killed. Several Isaf service members were wounded in the attack. There were no Isaf fatalities. The base is secured and fully operational."

Nad Ali was a Taliban hotbed when the UK first arrived, but has been regarded as one of the success stories in recent years, as British and Afghan forces have taken control of the populated areas, driving the insurgents into the desert hinterland.

It is of the districts in Helmand that has been "transitioned" to Afghan control as Isaf steps back from frontline duties, leaving security almost entirely in the hands of the Afghans.