A judge's ruling was criticized yesterday for accepting a claim of self-defense from a burglar who injured a policeman trying to arrest him.

Pc Peter Scott was called to a house where an intruder was hiding in the loft. The officer told a court that Paul Reilly resisted arrest and assaulted him as he attempted to carry out his duty, punching him and then grinding his face into roof lagging.

Pc Scott was left with substantial facial injuries and Reilly was arrested only when another officer managed to get him in a headlock. Reilly, 27, appeared at Reading Crown Court last week and admitted assault occasioning actual bodily harm, but on the basis of self-defense.

The prosecution refused to accept the plea and Judge Stanley Spence held a special hearing, known as a Newton hearing, to decide if the basis of the plea was well-founded.

After listening to evidence, the judge said: "I cannot be sure the defendant was not acting in self-defense when he pushed Pc Scott."

As a result Reilly, a supermarket night-shift worker from Reading, will return to the court on Jan 29 to be sentenced on the basis that he may have been assaulted first in an unprovoked attack.

When details of the case were made known yesterday, Insp Martin Elliott, chairman of the Thames Valley branch of the Police Federation, said: "This is bizarre, giving the benefit of the doubt to the perpetrator as opposed to the victim of crime.

"My officers stick their lives on the line day in, day out to protect the public.

"Officers are industrious, hard-working people who are paid to tell the truth and they take their duty seriously."

Pc Scott insisted that it was an unprovoked attack, as did his colleague Pc Steve Purser who also attended the break-in at the house in Reading.

Pc Scott said Reilly ignored repeated orders to put his hands out. Instead, he claimed that Reilly knocked him over, pinned him down and then punched him at least six times, before grinding his face into roof lagging.

The officer said: "I was trying to breathe but gagging on the insulation.

"I realized I was in deep trouble and was of the opinion I was going to die."

Since the incident Pc Scott has lost a stone in weight and suffered post-traumatic stress disorder.

Martin Jackson, defending, said Reilly pushed Pc Scott and did not punch him. He claimed Reilly lost his balance and landed on top of the officer.

Reilly admitted a charge of handling stolen goods and another of burglary.