Soviet troops seized a police academy in Latvia Tuesday and the Baltic republic's government appealed to the world to prevent a Kremlin crackdown similar to the one already under way in neighboring Lithuania.

"At this severe hour, we are addressing all the nations of the world . . . not to allow another Kuwait to happen," the secessionist republic's leaders pleaded Monday.The appeal, broadcast on radio as the world braced for an expected war over Iraq's seizure of Kuwait, came after President Mikhail S. Gorbachev defended the Soviet army's bloody weekend assault in Lithuania.

It also followed demands by military and Latvian Communist Party officials that the separatist government resign and threats that they would replace it with a newly announced National Salvation Committee.

A faceless Kremlin-backed committee of the same name in Lithuania was trying with the aid of Soviet troops to wrest power from the republic's democratically elected government and impose restrictions on civil liberties.

For Baltic residents, the committees' appearance was reminiscent of 1940, when Moscow-backed bodies spearheaded the forced annexation of the three states.

Gorbachev told the Supreme Soviet legislature in Moscow Monday that he did not order the Sunday seizure of Lithuania's broadcasting center, during which 14 people were killed and 230 wounded.

But he nevertheless defended the crackdown, which was widely condemned by Western nations. The United States and some other countries said they were as a result reconsidering economic help for the ailing Soviet economy.

Expecting to be the next target, independence activists in the Latvian capital of Riga on Monday set up barricades of heavy trucks on streets and bridges around town - especially near parliament, the central telephone exchange and the republic's broadcast center.

Soviet troops shot out the tires of some of the trucks and firebombed others.

At 2 a.m. Tuesday, elite Soviet Interior Ministry troops seized a police academy in the suburb of Agenskalns, said Tia Karkils, a spokeswoman for the Latvian parliament.

"Some of the students were a little roughed up, but there were no serious injuries," she said.

The takeover came after the commander of Soviet military forces in the Baltics, Col. Gen. Fyodor Kuzmin, ordered Latvian police to hand in their weapons to central authorities.

The police have been loyal to the republic's pro-independence government.

In their "appeal to the governments of the world" issued late Monday, Latvian leaders said "reactionary circles of the Communist Party of the USSR and Soviet armed forces are preparing a murderous coup d'etat" in the breakaway Baltic states - Lithuania, Latvia and Estonia.

They warned that the coup could take place within 24 to 48 hours.