Swansea City are suing Russell Martin for breach of contract over his move to Championship rivals Southampton, WalesOnline understands.

As first reported by the Telegraph, the Swans are taking their former manager to the High Court, some nine months after his departure for St Mary's, in a dispute centred around the money paid for him and several other members of staff.

Martin's exit took place against a backdrop of disagreement over the compensation figure owed by the Saints. Swansea believed they were entitled to around £2m as per the terms of losing Martin to a Premier League club.

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However, Southampton argue their approach was made after they officially lost their top flight status, meaning they were entitled to pay a lesser fee, which is understood to be around half.

It's understood Swansea have already received that lesser fee, although they have long insisted they would pursue the larger amount they feel they're owed. Having grown frustrated by a perceived lack of action from Southampton and the Premier League, club insiders have stressed the hierarchy believe this is the only way of earning the sum they feel they're entitled to.

The Swans believe they have a strong case against their former boss, although it's not yet clear when it will be heard.

Martin had just over a year left on his three-year deal in south Wales before moving to St Mary's, with the club deciding to allow his exit in an effort to move on from the saga, which threatened to drag on for most of the summer.

The club eventually opted to appoint Michael Duff as his successor, but he was sacked in December and replaced by Martin's former assistant Luke Williams around a month later.