Industrial action at a south Wales steel plant has been stepped up in a row over pensions.

Union members at the Caparo steel works in Tredegar began "work to rule" action at 0600BST on Wednesday morning.

The ISTC is committed to putting its full resources behind our members in this campaign

ISTC General Secretary Michael Leahy

This move, which will see the workers withdraw their "goodwill and co-operation", follows the start of an overtime ban at the plant last week.

The results of a ballot on industrial action among workers at Caparo's Wrexham plant are still awaited.

ISTC general secretary Michael Leahy said management at Tredegar, and at Caparo's sister plant in Scunthorpe, had failed to listen to pleas not to scrap workers' final salary pension scheme.

"Our members at Caparo feel that they have no alternative but to escalate their industrial action," said Mr Leahy.

"They take this action reluctantly but with steely determination.

"The ISTC is committed to putting its full resources behind our members in this campaign."

A majority of ISTC members at both Caparo Merchant Bar in Scunthorpe and Caparo Natural Gas Tubes in Tredegar voted for strike action if necessary in defence of their pension scheme.

The ISTC have threatened strike action

Union members at Caparo Wire in Wrexham are currently being balloted on the issue.

Unless the matter is resolved, the union has given notice that one-day strike action will begin at Tredegar and Scunthorpe on Wednesday 17 July, and continue every Wednesday.

The dispute began when the company announced its intention to close its final salary pension scheme for existing employees and replace it with a stakeholder pension scheme.

Stakeholder pensions were launched in April last year as a low-cost way for those earning modest incomes to save for retirement, and ease the burden on state coffers.

Like other pension plans, money paid into a stakeholder pension is invested in items such as stocks and shares, bonds and cash savings accounts.

The Caparo Group of companies is owned by Labour Peer Lord Paul of Marylebone - and is part of the Caparo Industries Pension Scheme.

It is one of the UK's largest steel businesses with plants in Scunthorpe, Tredegar, Walsall and Wrexham.

ISTC represents members in current and former steel and metal communities.