MOSCOW, DEC. 18 -- The Latvian government said today that a series of mysterious explosions in its capital, Riga, were a Soviet provocation designed to pave the way for a military takeover of the rebel Baltic republic.

No one has been injured in the explosions, which came against a background of increasingly tense relations between the pro-independence government in Riga and the Soviet army. Most of the attacks have been directed against Soviet army and government institutions and memorials commemorating Latvia's incorporation into the Soviet Union during World War II.

The latest explosions took place Monday night near a monument to Soviet state founder Vladimir Lenin, the offices of the Latvian Communist Party and the military prosecutor's office. Latvian authorities have ordered increased security measures around Soviet buildings and monuments.

The Latvian mission in Moscow accused "forces hostile to the Latvian people" of carrying out the attacks in order to create an impression of disorder. The mission's statement said the bombers were "organized and supplied with an arsenal of propaganda and military supplies," implying that they had the backing of both the army and Communist Party hard-liners.

"The scenario of the provocateurs is quite clear. Their final aim is for the center {Moscow} to proclaim a state of emergency and the introduction of presidential rule in the republic," the statement said.

A sharply different theory of who might be responsible was aired tonight by Soviet television news. Its report included an interview with a Latvian army officer who implied that the attacks were the work of extreme nationalists hoping to provoke the army into "interfering in Latvia's internal affairs."

Like the neighboring Baltic republics of Lithuania and Estonia, Latvia proclaimed the restoration of its prewar independence earlier this year. Gorbachev has avoided substantive negotiations on the independence claim so far, arguing that all three Baltic republics should first hold referendums to test the extent of popular support.

With its 2.7 million people divided almost evenly between ethnic Latvians and Russian speakers, Latvia is likely to have difficulty in achieving a solid majority in a referendum on independence. The republic is also the most heavily militarized of the Baltic states -- both because it provides the Soviet Baltic fleet with several ice-free ports and because it has become a favorite place of retirement for Soviet army officers.

Attempts by the Latvian legislature to stop the influx of retired officers and reduce food supplies to military bases have incensed the Soviet high command. In a television broadcast last month, Defense Minister Dmitri Yazov appeared to single out Latvia for special condemnation when he said soldiers have the right to use weapons to defend themselves in the event of attacks on army bases or attempts by republics to cut off supplies.

Latvian leaders are currently in Moscow to attend a session of the Congress of People's Deputies. But they have announced that they will not take part in negotiations for a new treaty proposed by Gorbachev on the division of power between Moscow and the republics.