The four assembly members could face a police investigation

BBC Wales' Dragon's Eye programme revealed that the four AMs have been breaking the rules by not disclosing the nature of their partners' work.

The office of the assembly's presiding officer confirmed on Thursday evening that it has referred the matter to South Wales Police.

The AMs are : Ann Jones (Labour, Vale of Clwyd), Mark Isherwood (Conservative, North Wales), Jocelyn Davies (Plaid Cymru, South Wales East), Eleanor Burnham (Liberal Democrat, North Wales).

A spokesperson for Presiding Officer Dafydd Elis Thomas confirmed that the required action had been taken under the protocol of the National Assembly for Wales, South Wales Police and the Crown Prosecution Service on investigation of alleged offences relating to the register of interests.

In all four cases, the AMs were paying their spouses out of assembly funds.

But they failed to register that fact until this week.

If someone has failed to register an interest, then it's potentially a criminal matter Kirsty Williams AM

That is in breach of assembly rules, underpinned by criminal law.

The rules state that AMs must declare the occupation of their spouses and the penalty for not doing so could be severe.

Failure to fully disclose what an AM's partner does is a criminal offence punishable by a fine of up to �5000.

Kirsty Williams, chair of the assembly standards committee, said: "If someone has failed to register an interest whatever that interest is, then it's potentially a criminal matter.

"Any complaint that was received here at the National Assembly by the presiding officer would immediately be sent to the police for investigation."

All four members have now registered the fact they employ their spouses.

South Wales Police confirmed that the case had been referred to them.

In a statement, Chief Superintendent Jeff Cooksley said that a protocol existed between South Wales Police, the Welsh assembly and the Crown Prosecution Service with regard to such allegations and that the matter was referred to them on the basis of that protocol.