Media playback is unsupported on your device Media caption Undercover at the call centre. Footage: Channel 4

The Conservative Party has denied claims it broke electoral law by using a Neath call centre to canvass voters during the general election campaign.

An investigation by Channel 4 claimed the UK Tories contracted Blue Telecoms to conduct marketing campaigns ahead of the vote on 8 June.

The Information Commissioners Officer confirmed it would be asking the Tories about the calls.

A Conservative spokesman said all the calls were compliant with the law.

Blue Telecoms has been contacted for a comment.

An undercover investigation by C4 News, broadcast on Thursday, claimed the workers may have been carrying out paid canvassing, banned under electoral law, as they promoted key Conservative messages to undecided voters in the weeks before the election.

The investigation claimed that calls were made to voters in key marginal seats, including Bridgend, Gower, Clwyd South and Wrexham.

At the start of the election campaign, the information commissioner, Elizabeth Denham, contacted all parties to remind them of the law around direct marketing.

A Conservative party spokesman denied the allegations, saying: "Political parties of all colours pay for market research and direct marketing calls.

"All the scripts supplied by the party for these calls are compliant with data protection and information law".

A spokesman for the Information Commissioner's Office said it would take action against any party which had not "followed the law".

"We will be asking the Conservative Party about the marketing campaigns conducted from this call centre," he said.