The BBC was accused of censorship on Thursday when the Court of Appeal overturned a high court ruling which had prevented the screening of a political broadcast by a pro-life group.

Enough candidates stood for the Prolife Alliance in 1997 to allow it free broadcasts in Wales during the 1997 election. However, "in the interests of decency and good taste", the BBC decided not to show the commercial, which featured images of abortion.

However, Lord Justice Laws ruled that this was illegal.

"The common law requires that the freedom of political speech to be enjoyed by an accredited party at a public election, most especially at a general election, must not be interfered with save on the most pressing grounds, and such grounds will very rarely be shown by appeal to considerations of taste and decency alone," he said.

"Was there a pressing social need to ban this broadcast? I have reached the clear conclusion that there was not. Disturbing, perhaps shocking, though the images on this video undoubtedly are, they represent the reality, the actuality, of what is involved in the abortion process.

"To campaign for the prohibition of abortion is a legitimate political programme. The pictures are in a real sense the message. Words alone cannot convey the essentially human character of the foetus and the nature of its destruction by abortion," he said.

The chief political advisor to the BBC, Anne Sloman, said the corporation would take the case to the House of Lords.

"We are very concerned about the effects of this decision. The broadcasters have been entrusted by parliament with the obligation not to broadcast material that offends against good taste and decency or is likely to be offensive to public feeling," she said.

"This obligation has effectively been overridden by the Court of Appeal for the purposes of party election broadcasts save in the most exceptional of circumstances. This means that viewers may be subjected to material that will cause widespread and gross offence."

The leader of the Prolife Alliance, Bruno Quintavalle, welcomed the decision.

"This judgement signals the beginning of the end of legal abortion in the United Kingdom. Once our country sees the truth, they will know that abortion even in the earliest stages is an act of terrible violence which kills a human being. When the history of the repeal of abortion comes to be told, people will look back at the courageous judgement of the Court of Appeal as a decisive turning point," he said.