Residents are angry over the levels of smells coming from the site

About 35 people demonstrated and held up lorries at the entrance of the former Penrhos tip in Caerphilly.

They said that foul-smelling gases are still being released more than a month after the work was expected to be completed.

But the contractors say the claims about smells are unfounded.

During the 1950s and 1960s, tonnes of chemical waste including cyanide and acid drums, was dumped at the 60-acre Penrhos site.

Over the last few months, 100,000 tonnes of waste have been removed from the site, which is earmarked for a housing development with leisure facilities.

Several lorries were held up as protestors blocked the site entrance

In July, contractors cleaning the toxic waste dumped at the site paid for a masking agent to hide the smell from the tip.

But people living nearby said the problem was making people's lives a misery

Christine Jones, who lives close to the site, said: "It has been going on for such a long time and people are fed up of it," she said.

"You can't hang your washing out, because the smell sticks to the clothes.

"And we can't even open the windows in the hot weather because the smell is so bad.

The long-term benefits of the remediation and redevelopment of the site will outweigh the short term inconvenience to the local community Caerphilly Council

Ms Jones and other residents living nearby gathered at the entrance of the site on Friday morning for an hour holding up several lorries which were being used for the clear-up.

Another one of the protestors, Leanne Brain said the smell was "absolutely terrible".

"We feel like prisoners in our own homes because the smell is too bad to go outside into our gardens," she said.

Walters UK, who are clearing the site, have said they visited neighbouring housing estates on Thursday and were unable to detect any smells.

Spokesman Dave Thursfield said that monitoring stations on the perimeter of the site were not showing "untoward readings".

A number of protestors gathered at the site

And he added that vapour monitor readings within the site also showed nothing.

Mr Thursfield said that the major clearance of chemicals from the site was completed by 15 July, and the only thing remaining which could cause a smell is the decommissioning of the water treatment plant and minor tidying up in the area.

Hundreds of complaints have been made to Caerphilly Council about the smell.

In a statement, the council said: "The local authority and its consultants are regularly in contact with the developer in order to mitigate the odour problems.

"On balance, the long-term benefits of the remediation and redevelopment of the site will outweigh the short term inconvenience to the local community."