A council is facing a £5m bill for trying to evict "human moles" who have burrowed 20ft underground.
The eco-warriors have taken to the labyrinth of steel and concrete-fortified tunnels in protest at a proposed £90m dual carriageway in Essex which they fear will become an "M25 by stealth".
The five men, three of whom are seasoned tunnellers, claim to have food and water to last eight weeks and hope to beat the current record of 22 days for remaining underground, held by "Disco Dave", an activist in the protest against the second runway at Manchester airport.
But Essex county council is determined to drag the protesters out as soon as possible, even though it could cost it £5m. Around 25 activists have already been dispatched after bailiffs, armed with a court order, moved on to the site of the proposed A310 at Rettendon on February 6.
Some of the group, who set up camp last May, were pulled from trees, but the hard core retreated underground. A dozen specialist cavers and tunnellers now have to dig alongside them, or widen the passages, before they can pull them out.
Last night a spokesman for the under-sheriff of Essex admitted that the process was laborious. "We know there is one main shaft and two tunnels off it. But how long they are is a mystery, and we don't know how long this will take until we can find that out."
"Pordric", a spokesman for the activists, said the evictors had "a big shock ahead of them. The main shaft goes 16ft down, and then the tunnels lead up, go along, go down, wiggle up. The tunnels are 'worm holes' the width of a man, through which they crawl, but they're very complicated."
He said the authorities were pumping fresh air to the men - who could number more than five. They had eight weeks' supply of bottled water and other supplies. They had even constructed a toilet in a pit at the bottom of the central chamber, with air vents to the surface.
As for the residents of the traffic-congested villages to be bypassed, their tolerance has vanished.
"The protesters may have had some sympathy when they arrived to make their point," said a Rettendon villager last night. "But now everyone just wants them to go away so we can eventually get our peaceful lives back."
Meanwhile, up to 20 protesters remained under siege last night at Etheldore Heath, a second Essex environmental protest site, where security guards drafted in by a property developer have cordoned off activists and threatened to arrest supporters approaching the 8ft-high wire corral.
These eco-warriors are protesting at the construction of 60 homes on 11 acres of scrubland inhabited by rare wildlife. They claim the developers, Countryside Residential, are trying to "starve them out."
