PARIS -- The French government announced new steps in its battle against AIDS last week, putting fresh emphasis on blood tests.

Within two months, the government will open centers for free AIDS antibody testing with guaranteed anonymity in each of France's 95 departements, or counties. The number of information and care centers will be doubled. Letters are being sent to every physician in the country encouraging them to systematically propose AIDS testing to their patients as part of prenuptial exams, prenatal exams and before undergoing any surgery or invasive diagnostic tests.

In announcing the $166 million program, the French health minister, Michele Barzach, said testing "must remain voluntary, consented to freely and covered by medical confidentiality." Barzach has consistently opposed mandatory testing.

With 3,073 AIDS cases since 1981, France usually registers the second-highest number of cases worldwide, behind the United States, which has had more than 50,000. Brazil and Uganda have about the same number as France. Barzach said that between 150,000 and 250,000 French people are thought to be carrying the virus without showing symptoms yet. She forecast 10,000 to 15,000 cases by 1989.

The health minister called the results of the French information campaign encouraging. Since France authorized the advertising of condoms last year, sales of the contraceptive, which helps protect against AIDS, have increased by 38 percent.

AIDS also can be transmitted through the sharing of bloodied needles by drug addicts, and France has allowed pharmacies to sell syringes over the counter, without a prescription. In the areas of the country most exposed to AIDS, Barzach said, the purchase of clean syringes has more than doubled.

Many more people are also volunteering to be tested. The number of AIDS tests purchased in France tripled between 1986 and 1987, to 2.3 million.

The French health minister's report was well-timed. Today, health ministers from more than 130 countries are gathering in London under the auspices of the World Health Organization and the British government to discuss strategies for public information and education on AIDS.