BAGHDAD, Iraq - Iraq handed over to the United Nations office here yesterday a list of more than 500 experts involved in the development of ballistic missiles and nuclear, chemical or biological weapons, setting the stage for one of the knottiest tasks facing the renewed inspections.

The list fulfills one requirement of the U.N. Security Council's Resolution 1441, which was passed last month and re-established weapons inspections.

But the extent to which these scientists will prove helpful in ferreting out new information about Iraq's possible weapons of mass destruction remains an unanswered question.

The second Iraqi scientist interviewed by the nuclear inspectors - even before the United Nations was given the list - suggested at a news conference yesterday that all Iraqi scientists should demand that a witness from the government be present at interviews with inspectors and that no one should leave the country to be interviewed.

"How can an Iraqi man leave Iraq?" the scientist, Kadhim Mijbel, a British-educated metallurgist involved in developing light battlefield rockets, asked derisively.

His appearance was seemingly intended to suggest how Iraq expects all its scientists to behave. The subject of interviewing scientists is one of the most contentious provisions of the resolution. During past inspections, Iraq repeatedly declared that it had released a complete list of its weapons, only to have defectors disclose extensive hidden information.