SEOUL, South Korea (AP) _ Prime Minister Lee Han-key today apologized to the nation for the torture death of a student dissident at the hands of police.

Lee issued the apology in a radio address one day after three senior police commanders were charged with covering up the January killing of Park Chong- chol.

''On behalf of the government, I express a deep sense of shame over the facts that a tragic incident occurred in a country which subscribes to democracy and respects human rights,'' Lee said.

But he warned against any opposition attempt to use the case to foment opposition to the government of President Chun Doo-hwan.

The unfolding cover-up has prompted widespread student demonstrations and clashes between police and protesters.

''Now that the truth about the incident has been clearly and fully determined and ample political and legal action has been taken accordingly, there must never be any attempt to use it politically,'' Lee said.

He warned of a crackdown on opposition, saying a strong government stance was necessary to safeguard the 1988 Seoul Olympics and a trouble-free transfer of power when Chun, a former army general, steps down in February.

Lee's warning was aimed at a nationwide ''resistance'' campaign planned by opposition groups for June 10, the day the ruling party holds a convention to pick a presidential candidate. Opposition leaders said they will launch nationwide demonstrations that day to protest the cover-up as part of their demands for direct presidential elections.

The opposition is demanding Chun repeal his April 13 decision suspending talks on constitutional reform. It also threatens to lead a boycott of president elections at the end of the year unless the constitution is revised to allow a direct vote instead of the existing electoral college system.

Religious, intellectual and human rights groups have joined opposition politicians to form a major new alliance to challenge the government.

The alliance followed nationwide public anger over the torture case that led to the dismissal of the prime minister and other key ministers this week.

Lee, who replaced Lho Shin-yong in the Cabinet shakeup, said the government ''has deeply reflected over the incident and that more effective legal and institutional safeguards for human rights will be worked out to prevent any recurrence of similar incidents.''

''It is truly regrettable and deplorable that the recent death of Park Chong-chol and the malfeasance committted in the course of investigaing him have caused great public sorrow and dismay,'' Lee added.

Prosecution officials said Friday that three police commanders, including the deputy chief of the National Police, were arrested for allegedly trying to cover up the number of officers involved in Park's death Jan. 14. Police have acknowledged that Park suffered extensive torture and beatings before he was suffocated.

Three junior officers were formally charged Friday for the torture of the student. Two other junior officers were charged near the time of the killing. The three commanders were charged Friday with bribing the first two officers to take all the blame for the killing.

Opposition leaders denounced the arrests as inadequate, claiming the cover- up went much higher and called for a broader investigation of the case.