British security forces news media to turn in tapes. NORTHERN IRELAND

Britain's television news media are caught in the crossfire of the Northern Ireland conflict. And as a result, journalists here are increasingly concerned for their independence and safety.

Yesterday, British and Irish television networks were forced to turn over their news tapes to the British government to assist police in identifying members of a Belfast mob who attacked two British soldiers last week.

The Northern Ireland police force, the Royal Ulster Constabulary (RUC), threatened to arrest senior television executives in Belfast if they did not cooperate.

The action by the RUC was taken under Britain's Prevention of Terrorism Act, which makes it illegal to withhold information in such cases.

Further, a British Broadcasting Corporation television crew was threatened Wednesday by pro-British loyalists in the town of Lisburn, and retreated after police said they could not protect them. Observers said the harassment came because the London-based ITN (Independent Television News) and the BBC initially had refused to cooperate in handing their tapes over to the authorities.

The police gathered the materials after Prime Minister Margaret Thatcher warned the networks not to obstruct attempts to bring the murderers to justice.

``Either one is on the side of justice in these matters or one is on the side of terrorism,'' Mrs. Thatcher told members of Parliament earlier this week.

TV journalists are concerned their independence has been compromised and it no longer is safe to cover news events in certain parts of Northern Ireland.

``We would argue that in consistently telling the truth about this situation, we are already making a very great contribution,'' said Colin Morris, BBC's Belfast controller. ``But the price of telling the truth is that our independence from any official body should be clearly demonstrated.'' Mr. Morris said he doubted the BBC's crews would be shut out of certain areas of Ulster if the network complied with the law.

Some Belfast observers say the BBC and ITN have cut themselves off from reporting events such as last week's funerals by the outlawed provisional Irish Republican Army.

``There's no way the IRA will permit the press to take pictures if they're going to turn them over to the police,'' said a resident of west Belfast, where last week's violence took place.

But one television executive said the IRA funerals were a public display made for television and that there was no point in staging them if they could not be broadcast on the evening news.