The Ministry of Defence said an investigation was under way into the soldiers' deaths at a checkpoint in the south of Nahr-e Saraj on Saturday, and it could not comment.
But last night sources said the killer lured the men, from 3rd Battalion The Yorkshire Regiment, to their deaths after pretending he had an injury.
The deaths, following that of Lance Corporal Duane Groom from 1st Battalion Grenadier Guards on Friday, are the latest in a series of "green on blue" attacks, where members of the Afghan security services have attacked coalition troops.
They came on a day four US marines were killed in a similar attack when at least one Afghan policeman turned his gun on Nato troops at a remote checkpoint in the country's south.
An MoD spokeswoman said: "It is with sadness the Ministry of Defence must announce the death of two soldiers from Third Battalion The Yorkshire Regiment on Saturday September 15.
"The soldiers were shot and killed by a man wearing the uniform of the Afghan local police at a checkpoint in the south of Nahr-e Saraj district, Helmand province."
The soldiers' next of kin have been informed, the MoD added.
Major Laurence Roche, of Task Force Helmand, said: "The Yorkshire Regiment has suffered a deep loss today and everyone serving within Task Force Helmand will want to send our condolences to the soldiers' families and loved ones at this time."
The deaths bring the total losses from UK forces since operations in Afghanistan began in October 2001 to 430.
In an attack at Camp Bastion, where Prince Harry is based, two US Marines were killed on Friday night.
The attack was by 15 Taliban insurgents who witnesses said wore US Army uniforms. The group destroyed six Harrier jets and three refuelling stations and damaged aircraft hangars.
As well as the two US marines who died, the International Security Assistance Force (Isaf) in Afghanistan said nine coalition staff were wounded.
Coalition forces killed 14 insurgents and wounded one, who was taken into custody.
The attack happened just after 10pm on Friday. Taliban fighters, heavily armed and organised into three groups, breached the camp's perimeter.
The attack was near an airfield on the north-east of the base, which houses American forces. The Taliban later said it was in response to Prince Harry being deployed to Afghanistan, where he is serving as the pilot of an Apache attack helicopter.
A Taliban spokesman said: "We attacked that base because Prince Harry was also on it and so they can know our anger."
A Nato spokesman confirmed Captain Wales, as he is known in the army, was on the sprawling base at the time of the attack but had never been in any danger.
An Isaf spokesman said: "The insurgents appeared to be well equipped, trained and rehearsed.
"Dressed in US Army uniforms and armed with automatic rifles, rocket propelled grenade launchers and suicide vests, the insurgents attacked coalition fixed and rotary-wing aircraft parked on the flight line, aircraft hangars and other buildings."
The official said the six Harrier jets destroyed were US marine aircraft. Two others were badly damaged, along with six aircraft hangars.
The nine personnel who were wounded included eight military and one civilian contractor, Isaf said. None of the injuries is thought to be life-threatening.
Lance Corporal Groom was killed on Friday.
The soldier, from Fiji, was killed when his vehicle struck an improvised explosive device in the Nahr-e Saraj District of Helmand Province.
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