THE Environment Agency is reviewing its procedures after escaping prosecution for destroying part of a 300-year-old ancient monument.

The agency could have faced an unlimited fine for bulldozing walls and floors at Rookhope Old Smeltmill, in Weardale, when it dug lagoons to prevent toxic minewater wiping out wildlife in a nearby stream.

The earthwork remains, which included a wheelpit, buried deposits and artefacts, provided invaluable information on the technology of early 19th Century lead smelting.

However, the earthmovers left intact the remains of a rare Elizabethan smelting operation lying alongside.

Following the destruction of the relic in late 1999, the agency was criticised for failing to check its own list of monuments or wait for advice from archaeological experts.

It says it will review its internal procedures and liaise with other agencies more closely in future.

It has also agreed to fund further archaeological research at the mill, which was built in about 1700 to process the valley's lead ore and had lain undisturbed since it was abandoned in the late 1730s.

English Heritage, which designated the mill an ancient monument in 1997, has told the agency it will not resort to court action.

Regional director Peter Bromley told bosses: "The reasons for this are mostly a reflection of the positive way you have responded after the scheduled monument was damaged, and your work to find ways of avoiding such problems in future."

An agency spokesman said: "The agency acted in good faith to prevent pollution of a nearby stream.

"The work was urgent and it proved to be effective in preventing toxic water polluting Rookhope Burn.

"The action that we took did have consequences for historic remains and that was regrettable.

"However, lessons have been learned.