MPs today vowed to continue the battle to protect the Shropshire and Mid Wales countryside from plans which could see power lines built across the region.

The pledge came after a delegation of MPs and council bosses met National Grid boss Nick Winser at Westminster yesterday. He revealed that burying the cables would cost three times as much as using overground cables.

It had previously been suggested it could cost up to 10 times as much.

The delegation, MPs Owen Paterson, Glyn Davies, Philip Dunne and Daniel Kawczynski along with Shropshire Council leader Keith Barrow and chief executive Kim Ryley, insisted any cables must go underground.

The National Grid wants to build a 400,000 volt electricity line from either Abermule or Cefn Coch in Mid Wales along one of 10 suggested routes across the Shropshire countryside.

Mr Paterson said that during “spirited” about the cables it was confirmed that burying the cables would cost £562 million compared to £178 million overground.

“We made clear the very strong and widespread hostility to this project,” he said. “If the cables have to run through Shropshire, they simply must be placed underground to protect the countryside.”

Mr Davies, Montgomeryshire MP, said: “National Grid made clear that the opinions of local councillors or of the National Assembly carried no relevance and no matter what the people of Mid Wales think, they intend to carry on. This is going to be a long war of attrition.

“Previously we had been given all sorts of costs but the reality is that the cost of undergrounding would be just three times the cost of a line of pylons.”

The Grid also revealed its planned timescale. It will go through the 6,000 to 7,000 consultation responses before announcing its preferred route in 2012.

It will then carry out an environmental survey, which will consider underground cables, before sending a recommendation to the Secretary of State in 2014. A decision is due in 2015.

Mr Dunne said: “I was pleased to have the opportunity to make it clear to the National Grid the grave concerns of the people of Shropshire.”

Councillor Barrow said: “It was a useful meeting that gave clarity and the timescales involved.”

By Chrissy Symmonds