Teesport is one of the largest in Europe

The Middlesbrough company, which owns and operates the ports of Tees and Hartlepool, is Britain's second-largest port by volume.

It is being bought by an alliance of private equity group 3i and Australian financial services firm Challenger.

PD Ports has been urging the government to allow the development of a deep-sea container terminal at Teesport to boost the North East's economy.

Challenger and 3i have set up a new company called Endeavour Ports, pledging to invest in the core operations of PD and focus on retaining and developing existing contracts with customers.

Land and property

Graeme Bevans, a director of Endeavour, said: "We are committed to long-term investors and we fully appreciate PD Ports' commercial importance to the North East of England."

Challenger currently owns stakes in firms ranging from the North of England Gas Distribution Network, Wales & West Utilities and gas transportation firm Inexus.

Endeavour says one of the attractions of PD Ports was its stock of land and property.

As well as the ports of Tees and Hartlepool, PD Ports runs a port services arm with operations in warehousing, distribution and freight forwarding from several UK locations.

PD chairman David Harding said: "We are satisfied that the new owners are serious, long-term investors in a ports business such as PD Ports."