Services of remembrance have been held in the UK and the Middle East for the Royal Marines and Royal Navy personnel who died in accidents in the first days of the war in Iraq.

Eight members of 3 Commando Brigade died early on Friday morning when their US Marine Corps CH-46 Sea Knight helicopter crashed in northern Kuwait while transporting troops as part of the assault on the strategically important Al-Faw peninsula.

Four American crewmen also died in the crash, which Coalition commanders say was the result of an accident rather than enemy action.

The following day two Sea King helicopters of 849 Naval Air Squadron, embarked in HMS Ark Royal, collided over the sea in the Northern Arabian Gulf, killing six Royal Navy personnel and one American.

The names of those killed in both incidents have not yet been released to the media by the Ministry of Defence.

Following the Sea Knight crash, Maj Keith Tuppman made the following statement on behalf of 3 Commando Brigade:

”You will be aware that in the early hours of [Friday] morning eight members of 3 Commando Brigade lost their lives on operations in the Gulf. Our thoughts and prayers are with their families and friends.

”3 Commando Brigade is a close-knit, family community and the loss of our colleagues is deeply felt by us all. I would like to pay tribute to their professionalism and dedication.

”While we have lost good friends and feel a profound sense of sadness at this time, we remain committed to our mission to bring peace and freedom to the people of Iraq.

”We are very grateful for all the support we have received from the people of Plymouth and surrounding communities. It means a great deal to us all.”

The Sea King crash, over international waters at around 1.30am UK time, involved two airborne surveillance and control Mk 7 aircraft, based at RN air station Culdrose, near Helston in Cornwall, which were making their operational debut.

The collision is believed to have happened as one aircraft returned to the carrier and the other was flying outbound, having just refuelled.

A rescue operation was launched within minutes of the crash, with Lynx helicopters and other ships, including minesweepers HMS Brocklesby and USS Dextrous searching for survivors as well as wreckage which could help indicate what caused the collision.

The Commanding Officer of HMS Ark Royal, Capt Alan Massey, described the collision as “a huge loss.”

Captain Mike Knowles, Commanding Officer of RNAS Culdrose, said: “Everybody is devastated by the news. In truth we are still coming to terms with what has happened. The shock is still reverberating through our community here.”

A memorial service was held yesterday morning on board HMS Ark Royal for the personnel killed in the mid-air collision. Capt Massey spoke of the frustration felt by the ship’s company at losing comrades in a “disastrous” accident, adding that “these men died in fully-fledged combat operations, pursuing a just cause in the tradition of the Royal Navy.”

Former Navy Sea King pilot the Duke of York has also expressed his sadness at the deaths.

Prince Andrew, who flew Sea Kings in the Falklands War, sent his condolences to their families, saying that he was "shocked and deeply saddened."

A statement from Buckingham Palace said: "As a helicopter pilot with combat experience, the Duke wishes to send his prayers and thoughts to the families of the bereaved."

Flowers were laid and the flag lowered to half mast at Culdrose, where a Royal Navy spokeswoman said: “The fleet air arm is a close community. As you can imagine we are all saddened by the situation."

Culdrose Commanding Officer Capt Mike Knowles said: "There is a large family at Culdrose and that family actually extends out to all the ships that are serving and so everybody is going to be affected by this ... it really is very, very sad news."

Downing Street expressed "deep sadness" at the loss of more military personnel.

Royal Navy and Royal Marines units were prominent in the earliest stages of the campaign over the weekend.

40 Commando Royal Marines began an assault on the southern tip of the Al-Faw peninsula, using support helicopters from Kuwait and from the ships of the Amphibious Task Group in the North Arabian Gulf, which includes helicopter carrier HMS Ocean and aircraft carrier HMS Ark Royal, which was configured as a helicopter carrier for this operation.

The tip of the peninsula, where oil pipelines from the significant oil fields in Southern Iraq terminate at a trans-shipment installation, was secured as planned.

Coalition ground forces including elements under the command of 3 Commando Brigade, were also involved in the operation to seize the port of Umm Qasr and a nearby naval base.

In addition, 42 Commando deployed in British aircraft to a blocking position north of the peninsula.

Throughout the entire operation, Royal Navy ships - including Type 22 frigate HMS Chatham and Type 23 frigate HMS Marlborough - provided naval gun-fire support to 3 Commando Brigade using their 4.5in guns, and Royal Navy submarines fired Tomahawk Land Attack Missiles (TLAM or cruise missiles) at targets in Baghdad in the opening bombardments.

Umm Qasr, which is roughly equivalent in size to the city of Southampton, is a key factor in the economic future of southern Iraq, and Royal Navy mine countermeasures vessels HM ships Brocklesby, Blyth and Bangor have been on mine clearance operations to provide a safe access route into the port.

Fleet clearance diving teams have also been at work ensuring the port itself is safe for Coalition shipping.

This will allow both support ships for the military campaign, and ships carrying humanitarian supplies, to unload more efficiently than standing out to sea.

In another sector of the war, two RAF air crew died in a “friendly-fire” accident.

Their Tornado GR4 bomber was shot down by an American Patriot air defence missile near the Kuwaiti border. A major investigation by British and American forces is under way.

The so-called "blue on blue" incident happened as the Tornado was returning from a mission over Iraq.