Gov. George Deukmejian signed a landmark oil spill bill Saturday that taxes oil 25 cents a barrel, creates a cleanup "czar" and regulates tankers in California waters.

Deukmejian said the new law "will give California an unprecedented ability to prevent spills before they happen and to fight the effects of spills if they do occur."The Republican governor, who earlier had expressed reservations about some aspects of the bill, announced the signing during his weekly radio address.

The bill was the object of intense negotiations among legislators, the oil industry, environmentalist groups and trial lawyers all year. It was passed Aug. 31, the last day of the Legislature's 1990 session.

The new law, which takes effect immediately, will tax crude oil 25 cents a barrel. That money will go into a $100 million cleanup fund. Backers say it will take about six months to bring the fund to $50 million. Then some of the money will be used to secure a line of credit for the other half.

The governor will appoint a state oil spill response administrator or "czar," who will develop rules and regulations for safe transportation of oil. The administrator will head a new Office of Spill Preparedness, which will combine the existing powers of 14 state agencies.

The law allows the state to conduct surprise inspections of tankers and terminals, requires up-to-date safety plans for refineries and requires tugboat escorts and radar tracking of tankers.

One of the stumbling points in the negotiations was the amount of liability that private cleanup contractors, especially those hired or created by oil companies, should have during the cleanups themselves.

The oil industry wanted permanent immunity from lawsuits and fines for the cleanup contractors, but trial lawyers opposed immunity except for volunteer groups.