The protesters first moved onto the site on the outskirts of Pontardawe early on Monday morning before contractors arrived.

They say they are willing to stay inside the pipe for "as long as it takes" in a bid to halt construction.

The pipe will carry natural gas from two LNG plants at Milford Haven in Pembrokeshire to join the national gas network in Gloucestershire

The protesters, who have set up camp about 300 yards from the pipe, are a mix of local villagers and supporters from further afield.

No work was being done at the site on Tuesday with police and National Grid officials keeping their distance from the protest.