Retained firefighters in Wales are still at risk of intimidation by their striking full-time colleagues, according to their union, the RFU.

Tension between the two groups of firefighters - many are still manning appliances - erupted last month when RFU members in south Wales received letters calling its members scabs.

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Now the union claims that RFU firefighters are being told that they will not be able to become full-time firemen in the future if they work during the strike.

The Fire Brigades Union denies its members have tried to intimidate members of the RFU.

But Derek Chadbon, National General Secretary of the Retained Firefighters Union, said fire service managers have turned a blind eye to pressure put on part-time firefighters.

He said managers did not want to upset the full-timers' union.

He said: "We've had a number of cases of retained firefighters, many of whom aspire to be full-time firefighters and who have great difficulty getting in, being told things like 'you've got no chance unless you join the Fire Brigades Union'.

"It appears to be a common thread that is being picked up in a great number of places.

'Scab' letter

"I can only assume therefore that there may be some sort of coordination behind it."

He said the 'scab' letter sent last month - a copy of a poem written by the novelist Jack London - had led to a number of part-timers switching to the FBU.

"The management have been encouraging them on the grounds that they don't want to upset the FBU.

"It gives the management an easier life after the strike if there is no disharmony between retained and whole-time firefighters."

Mr Chadbon also said members of the public might be able to sue the fire service if they could prove a minor fire which might have been put out by retained firefighters had become a large fire because the part-timers had not turned out.

The Fire Brigades Union has always denied its members have tried to intimidate their part-time colleagues.