US SENATOR Hillary Clinton has stepped in to block the sale of part of Southampton docks to a Dubai company.

National security concerns in America prompted Mrs Clinton - wife of former president Bill Clinton - to oppose the £3.92 billion deal for P&O.

The ports group, which owns a half share in Southampton Container Terminals as well as a number of ports in America, had agreed to sell up to state-owned Dubai Ports World.

Although the Bush administration has approved the sale, Mrs Clinton, right, and fellow Democratic senator Robert Menndez have introduced a bill aimed at preventing the sale. Their legislation would ban companies owned or controlled by foreign governments from acquiring US ports.

Mrs Clinton said: "Our port security is too important to place in the hands of foreign governments."

Mr Menndez added: "Our ports are the front lines of the war against terrorism.

"We wouldn't turn the border patrol or the customs service over to a foreign government, and we can't afford to turn our ports over to one either."

Port security has been thrown into focus in the aftermath of the September 11, 2001 attacks, with sea-borne container trade the lifeblood of the world economy.

The objections to the deal come late in the three-month process after the bid had been agreed by shareholders.

P&O, the world's fourth-largest ports company, runs commercial operations in New York, New Jersey, Baltimore, New Orleans, Miami and Philadelphia. The company employs 800 people in its Southampton operation, which it owns jointly with Associated British Ports.

P&O's partner in a similar venture in Miami, Eller & Company, has filed a £5.7m lawsuit against P&O, claiming that it was not consulted about the deal and was faced with the prospect of becoming an involuntarily partner of DP World.

A P&O spokesman said: "We're confident all issues have been satisfactorily addressed."