13 July 2012 Last updated at 08:26 ET

London 2012: Welsh Cavalry and 1 Rifles soldiers on standby

Soldiers from the Queen's Dragoon Guards are being drafted in to bolster Olympic security

Hundreds of troops from two Wales-based elements of the Army are set to take on Olympic security work.

The Queen's Dragoon Guards (QDG), known as the Welsh Cavalry, and 1 Rifles have been called up amid concerns over staff shortages at security firm G4S.

The UK's armed forces are on standby to provide an additional 3,500 troops for security at the 2012 London Olympics.

The first Olympic event is a women's football match at Cardiff's Millennium Stadium on 25 July.

The game is one of 11 Olympic matches to be staged at the venue.

Cancelled leave

Extra troops are being drafted for security work in amid fears that private contractor G4S would not be able to provide enough trained staff in time.

The Army in Wales confirmed that the Queens Dragoon Guards - known as the Welsh Cavalry - and 1 Rifles were being put forward for security cover for Olympic events across the UK.

The QDGs are based in Germany while 1 Rifles are an infantry battalion whose Gloucestershire barracks have a Chepstow postcode, putting them under the administrative control of the Army at Brecon.

More details about the deployments are expected to be announced on Monday.

The armed forces are already providing some 13,500 personnel - this could now reach 17,000, meaning summer leave for some troops is likely to be cancelled.

This month it was announced that the QDGs, along with the Royal Welsh and the Welsh Guards, are to survive planned cuts to the army.

Last month soldiers from 1st The Queen's Dragoon Guards marched through Cardiff as part of the Queen's Diamond Jubilee celebrations.