MPs will be updated on security in Afghanistan today, following the deaths of three British soldiers and an assault on the UK’s main military base in the country over the course of the last few days.

Defence Secretary Philip Hammond is expected to respond to an urgent question from Labour MP Denis MacShane in the House of Commons.

Married father-of-two Sergeant Gareth Thursby, 29, and Private Thomas Wroe, 18, of Meltham, were shot dead in the south of Nahr-e Saraj district, Helmand province, on Saturday, in what appears to be the latest in a string of "green-on-blue" incidents.

The soldiers, from 3rd Battalion, The Yorkshire Regiment (Duke of Wellington’s), were killed at a checkpoint when a man dressed as a local Afghan policeman pretended to be injured so they would help him.

On Friday, Lance Corporal Duane Groom, from 1st Battalion Grenadier Guards, died after his vehicle hit a roadside bomb.

On the same day, two US Marines were killed during an attack on Camp Bastion, the desert base in Helmand province where the bulk of the UK’s 9,500-strong force in Afghanistan are deployed.

Taliban sources later claimed that Bastion was targeted because Prince Harry is serving there on his second tour of duty in the country as an Army captain. The Prince was about two kilometres away with other crew members of an Apache attack helicopter and was not harmed.

The attack was by heavily-armed insurgents and involved a range of weaponry, including mortars, rockets or rocket-propelled grenades, as well as small arms fire, said US military sources.

This weekend’s deaths brought the total number of members of UK forces to have died since operations in Afghanistan began in October 2001 to 430.

Mr Hammond said he was "saddened" to hear of the "cowardly" attack by a man wearing police uniform. The Ministry of Defence said an investigation was under way into the circumstances of the soldiers’ deaths.

Sgt Thursby, from Skipton, North Yorkshire, had completed tours of duty in Kosovo and Iraq, and was nicknamed Bull because of his strength and confidence.

His wife Louise said: "Gareth was the love of my life.

"He was an amazing husband and father, happy, full of life and kind-hearted, with a passion for his work and family. He was brave, hard-working, a loving husband who was a devoted father to his children. Our hero."

Pte Wroe was deployed to Afghanistan on July 1, shortly after his 18th birthday. He is survived by his parents, Michael and Claire, and sister Demi, from Meltham.

His family said in a statement: "Our son Thomas was a brave young soldier, who is loved by his family, girlfriend and friends.

"We can’t believe you have been taken so soon from us. You will always be in our hearts for ever and ever.

"You would light up the room with your smile and bubbly personality. Our world will be a duller place without you.

"We are so proud of you son, of all you achieved, and we are grateful for every special thing you gave us. We will always love you Tom."

Asked about the attack on Camp Bastion, Nato Secretary-General Anders Fogh Rasmussen told BBC Radio 4’s World At One: "It seems to have been a well-organised attack, but it is also a fact that all the attackers were killed or captured, and I don’t think the attack will have an operational impact on our mission in Afghanistan."

Mr Rasmussen insisted that Nato was sticking to its timetable of handing over control in Afghanistan to home-grown forces at the end of 2014, despite indications from Mr Hammond that troops may be withdrawn at a faster pace than expected next year.

"The strategy we are pursuing is the only strategy that makes sense," Mr Rasmussen said. "With the goal to let the Afghans take full responsibility for their own security by the end of 2014, we are now building up the number of Afghan security forces to a level of 352,000.

"Quality-wise, we train and educate them so they can take the lead of more and more security operations.

"It is not an accelerated timeline. We stick to the timeline we outlined two years ago, that in a gradual process we will hand over lead responsibility for security to Afghan security forces."

Mr Rasmussen acknowledged that the online film Innocence Of Muslims - which has provoked protests and riots in countries across the Islamic world - would be used by insurgents "as a bad excuse for attacking our troops" in Afghanistan.

But he insisted that "ordinary Afghans want peace and security" and said political talks with insurgents should be considered, as long as they are ready to renounce terrorism, respect the Afghan constitution and engage with the government in Kabul.

Mr Rasmussen said that "insider attacks" by Afghan security forces on the Nato troops who are training and mentoring them are "a matter of great concern".

He added: "We have taken and continue to take all the steps necessary to prevent such insider attacks, because they threaten to undermine trust and confidence between foreign troops and Afghan security forces.

"In order to prevent such attacks, we have strengthened vetting procedures and recruitment procedures and we will continue to do so if necessary."

Responding to a Nato airstrike said by Afghan officials to have killed eight civilian women collecting firewood in the east of the country yesterday, Mr Rasmussen said: "It is a very tragic incident and I convey my heartfelt condolences to the families.

"Having said that, I would also like to stress that we do all we can to minimise the number of civilian casualties and the fact is that a huge majority of civilian casualties in Afghanistan are caused by the Taliban."