KABUL, Afghanistan — An investigation was under way on Sunday to find out why a British military helicopter crashed in southern Afghanistan, killing five troops.

The Lynx helicopter crashed during a routine flight in Kandahar province on Saturday, causing the biggest single loss of life for British troops in the country.

Britain's Ministry of Defense denied claims from Taliban insurgents that they shot down the light utility helicopter, saying its initial investigations pointed towards a technical fault during the routine flight.

"The investigation is now under way, and the area of the crash has been cordoned off," an MoD spokeswoman said.

"We cannot go into further details. At this stage it is not known how long the investigation might last or when investigators will deliver their report, but it will be a thorough inquiry."

Experts said the inquiry was likely to examine the aircraft's log books and other documentation, in addition to weather conditions and whether the helicopter was conducting an authorized mission in accordance with its capabilities.

It is not thought that other Lynx helicopters in Afghanistan will be grounded.

The incident, "at this early stage, would appear to have been a tragic accident," said Major General Richard Felton, commander of the British armed forces' Joint Helicopter Command.

The loss, which comes just before the US-led International Security Assistance Force (ISAF) operation in Afghanistan comes to an end in December after 13 years, brings the total number of British fatalities to 453.

Prime Minister David Cameron described the deaths as a "terrible tragedy."

Local officials in southern Afghanistan told AFP the helicopter came down in Takhta Pul and was not attacked by militants.

"It was doing military exercises and crashed as a result of technical fault," said Zia Durrani, the provincial police spokesman.

The Taliban said on a recognized Twitter account that it had targeted the helicopter and the "wreckage caught fire as it smashed onto the ground, killing all invaders on board."

The insurgent group often makes erroneous claims of responsibility.

Aircraft crashes have been a regular risk for the ISAF mission in Afghanistan, with troops relying heavily on air transport to battle the Taliban insurgency across the south and east of the country.

British forces use Westland Lynx helicopters for a wide variety of operations, including transport and supply.