'Dirty tricks' fear after raid at Miliband's HQ

Door forced, drawers rifled and computers tampered with

Ed Miliband's 'policy office' is thought to be targeted (EPA)

Ed Miliband was at the centre of allegations of a "dirty tricks" campaign against him yesterday after Scotland Yard confirmed it is investigating a break-in at the Labour leader's offices at the Houses of Parliament.

Police were called to Mr Miliband's Westminster base on Friday evening after a member of staff reported that a door had been forced at the suite of offices in Norman Shaw North building.

Labour spokesmen and the Metropolitan Police refused to give more details about the investigation. The same area of Parliament has been plagued by thefts in recent months.

However, the incident has raised "deep concerns" within the party that the office had been deliberately targeted by someone looking for internal papers – on the eve of one of the most important weeks in the parliamentary calendar.

Mr Miliband and his senior team have been working on Labour's new policy programme for several months. Although, in recent weeks, their workload has been dominated by preparations for Labour's response to the Budget, which will be delivered by Chancellor George Osborne on Wednesday.

The Labour leader's headquarters include at least six offices leading off a central reception room. But the intruder is believed to have headed straight for Mr Miliband's "policy office".

"The policy office is not the first one you come to when you enter the suite, but it is where the interesting stuff is," one source close to the investigation said. "They were going through papers and trying drawers and computers. It looks like they were specifically looking for information." It remains unclear whether anything was taken from the room.

Scotland Yard confirmed that it had received a report shortly before 7pm on Friday night of a forced entry in the Norman Shaw buildings.

A Met spokesman said: "Police were contacted at 6.55pm regarding an alleged forced entry to an office in the Palace of Westminster. Inquiries continue."

Mr Miliband was away from his second-floor offices at the time of the break-in, attending a party conference in the Midlands.

A Labour spokesman said: "There is an ongoing police investigation. It would be inappropriate to comment."

The two seven-storey Norman Shaw Buildings, across the road from the main Houses of Parliament, were used until 1967 as the headquarters of the Metropolitan Police.

MPs with offices in the buildings have suffered a series of thefts that go back several years, with laptops, an orchid and a £1,000 candlestick among the missing items.

The Labour MP Keith Vaz, who works from the building, last year called for "more robust" security after a laptop and iPad were stolen from his office.

He said at the time: "I gather that whoever did this also took a laptop from another Member of Parliament on the same floor; and, since reporting it to the police, I am informed this happens quite regularly on the Parliamentary estate."

Mr Vaz, who is chairman of the Home Affairs Committee, said he had only seen one CCTV camera in the area – and that was in the car park.