LONDON - The British government is expected to make it a criminal offense to publicize the names or addresses of scientists, bankers and shareholders involved in drug testing on animals as part of a wider crackdown on animal rights militants.

After years of targeting individuals engaged in violent acts at the extremist end of the animal rights movement, ministers are now working with research groups and police to target the planning behind individual acts.

The British Home Office confirmed that the minister responsible, Mike O'Brien, is engaged in efforts to tighten a range of laws which fail to address such problems as criminal damage and harassment.

Such tactics extend to intimidating telephone calls at midnight, and to floods of unwanted goods that arrive at targets' homes.

"I once had 40 calls as a result of a small ad to sell my cement mixer. That was clearly harassment. After the 39th call I changed my telephone number," said Mark Matfield, spokesman for the Research Defense Society.

After O'Brien visited Huntingdon Life Sciences, Europe's biggest contract research company, he convened a meeting with police and scientific interests. The company's shares have slipped since fund manager Phillips & Drew sold its 11 percent share cheaply after a bomb threat in February.

Though tighter restrictions on the use of names and addresses is a frontrunner for change, the British Department of Trade and Industry is examining the implications for companies which must, by law, publish such details of shareholders.

Home Office officials distinguish legitimate public protest from the increasingly sophisticated violence, often attributed to the loosely designated Animal Liberation Front and associated bodies.

The 1997 Prohibition of Harassment Act, which has been used successfully against people who target fur traders, is being looked at again in the light of the 1,200 reported incidents of animal rights protest in 1999.

But the scientific community is convinced that those convicted of dangerous assaults do not get the sentences they might if their perceived "ideals" were not being taken into account.

Matfield said that the Animal Liberation Front had shifted its tactics in recent years away from car bomb spectaculars toward harassment campaigns against individuals associated with research, either as employees or investors.