One of East Anglia's finest ancient monasteries is set for a security upgrade following long-running problems with vandalism, graffiti and littering.The custodians of Thetford's 12th century Cluniac priory have submitted plans for new fencing, gates and the raising of a wall to help improve night-time security.

One of East Anglia's finest ancient monasteries is set for a security upgrade following long-running problems with vandalism, graffiti and littering.

The custodians of Thetford's 12th century Cluniac priory have submitted plans for new fencing, gates and the raising of a wall to help improve night-time security.

Heritage officials in the town yesterday welcomed the proposals from English Heritage, which comes a year after nearly £35,000 of European funding was wasted.

The plans, which also include car park improvements and tree works, have been submitted to Breckland Council following a history of youths congregating around the ruins at night.

English Heritage was granted £120,000 from the European Regional Development Fund three years ago, of which only £85,000 was spent on new security fencing, repointing works, stonework repairs, landscaping, and new information panels depicting Thetford Priory in it heyday.

However, the historic religious site continues to be vandalised as it is still not secure at night with no main gate or fencing on its western boundary.

Stuart Wright, chairman of the Thetford Society, said: "English Heritage has been promising security improvements for a year now and has been dragging its feet on money after it failed to spend £35,000 of European money in time.

"We welcome money being spent on the site, but English Heritage could do so much more with the site. It is one of the biggest and most important priories in East Anglia."

Campaigners say the nearby Abbey Barns complex at Monksgate is a "golden opportunity" to enhance the ruins with a visitor centre. However, a developer has submitted plans for a 26-home development on the site.

A spokesman from English Heritage said: "Thetford priory will remain open to visitors free of charge but if required the new gates will be locked overnight. We have allocated a substantial budget for the site, although the exact value is subject to commercial tender."

The priory was founded in the early 12th century and owed much of its prosperity to a miraculous appearance of the Virgin Mary, whose statue was discovered to conceal relics of saints, and became a magnet for pilgrims.

Two of the greatest men in early Tudor England, Thomas Howard, victor of Flodden, and Henry Fitzroy, illegitimate son of Henry VIII, were buried near her shrine.