MPs in the south are demanding answers from BT after the massive failure of the county's phone network on Thursday night.

Isle of Wight MP AndrewTurner has asked for a government minister to give a statement to the House of Commons on Monday about the breakdown in telecommunications which crippled the county's emergency services and left tens of thousands of householders across the region without telephones for five hours.

Mr Turner said: "I am seriously unimpressed with BT's performance. The failure of their back-up system is just unbelievable."

Romsey MP Sandra Gidley, who is demanding an inquiry into the failure, said: "The public is entitled to an explanation as to how and why this happened. The explanation given so far, that an electrical fault could cause such a failure, is totally inadequate. We must learn from the experience and ensure that back-up mechanisms are in place so that this does not happen again, either in Hampshire or any other area in the country."

Thursday night's chaos took place when tens of thousands of lines across Hampshire went dead after the power supply to a BT communications centre at Bargate in Southampton failed.

Police, fire, ambulance and coastguards were affected by the crash which took place at around 6.30 pm on Thursday night. The assistant chief constable of Hampshire, Colin Smith, said the crash should never have happened.

He said police would be talking to BT about why no back-up system had kicked into operation.

Thursday night's crippling failure saw extra police officers put on patrol in Hampshire and police stations remaining open all night as the scale of the crisis became apparent. Hampshire Fire and Rescue Service also put all 34 of its retained stations across the county on standby and drafted in an extra 20 officers to its headquarters to cope with the chaos.

Hampshire Fire and Rescue spokesman David Askew said the brigade had been "lucky" that Thursday had been a quiet night.

BT spokesman Jason Mann said the company had back-up power but the means of getting the power to the telecommunications system itself in the building had failed. He said: "It is extremely rare for this to happen. We are very aware of the inconvenience that has been caused. We are carrying out our own investigations. We did everything we reasonably could to restore services."