Laing O’Rourke is to be handed a 21-day payment ultimatum by Irish tycoon John Magnier over a disputed €50m property deal in Spain.

Magnier signed a deal with the contractor’s Explore Investments division in 2006 to buy a 50% stake in the scheme to develop the 3.6ha site in Marbella.

However, it emerged last week that Explore was embroiled in a court case in Ireland over a €3.5m payment that had been due in September.

A source close to the case claimed that Laing O’Rourke could wind up the division of Explore responsible for its share of the deal.

A spokesperson forMagnier said: “If the payment isn’t made then we will pursue the company directors and, if necessary, the parent for the money.”

Explore declined to comment.