The alleged former leader of the IRA has agreed to hand over a near £1m criminal assets portfolio to authorities.

Top Irish republican Thomas ‘Slab’ Murphy, and his brothers Frank and Patrick, handed over cash, cheques and properties to Irish and British revenue officers.

The three brothers and the Ace Oils |fuel company were targeted by police investigating a massive smuggling racket operating on both sides of the Irish border.

More than £487,000 in cash and cheques were confiscated in Ireland while nine properties in north-west England worth £445,000 were recovered by UK authorities. A garda spokesman said the settlement was the culmination of a global crime and fraud investigation into the proceeds of crime.

“These proceedings are the culmination of intensive investigations by the Criminal Assets Bureau and the UK's Serious and Organised Crime Agency,” gardai said.

“Both agencies have co-operated extensively, working in partnership to achieve today's outcome.”

The Irish leg of the investigation was settled in Dublin's High Court yesterday while the UK's seizure was finalised in a Manchester court on Thursday.

The three men were under investigation since March 2006 when ‘Slab’ Murphy's sprawling farm in Hackballscross, straddling the border between Louth and Armagh, was raided.

It was one of 15 residential and business properties searched as part of the operation.

More than £140,000 in mixed currencies, 30,000 cigarettes and 8,000 litres of fuel were seized while 30 archive boxes

Both agencies have co-operated extensively, working in partnership to achieve this outcome

of documents, three tankers and a truck with a fourth tanker concealed inside were impounded.An oil laundering unit was also seized in the probe.

More than 100 gardai, soldiers, customs and the fraud squad joined the PSNI in the dawn raid.

At the time, ‘Slab’ Murphy was being investigated by the Assets Recovery Agency over house sales in the Greater Manchester area.

It is understood the raid and subsequent Cab action severely damaged the IRA's money-making scams in the border area.

Sinn Fein president Gerry Adams later stood by the alleged former IRA chief and declared: “Tom Murphy is not a criminal. He is a good republican.”

In a separate investigation ‘Slab’ Murphy (58) faces nine charges of tax evasion for failing to furnish a return of his income, profits or gains over eight years from 1996.

He is now expected to try to block the trial in the High Court some time next month.