ATHENS — Greece’s conservative prime minister says he will undo a longstanding law banning the police from universities — a risky move for a new leader who came to power just weeks ago promising greater stability.

The law was passed in 1982, several years after the fall of the country’s military dictatorship, which had violently suppressed a student rebellion. Such a protection, which was meant to safeguard students and freedom of speech, exists nowhere else in Europe and is virtually sacrosanct in Greece.

But critics say it has been exploited over the years by self-styled anarchists and other militants, leading to violence and intimidation at universities, where, they say, homemade firebombs are often stored and later lobbed at police officers during street protests.

“Universities will be purged of firebombs, troublemakers and drug dealers and will return to students, professors and employees,” the new prime minister, Kyriakos Mitsotakis, told Parliament on Saturday, outlining his government’s priorities, which include greater public safety with heavily armed police officers in the capital.