MOSCOW -- Bulgaria joined the Soviet Union today in a boycott of the Los Angeles Olympics amid reports that Moscow's allies are organizing an alternative 'Red Olympics' for communist athletes.
In a statement monitored in Vienna, the Bulgarian National Olympic Committee said it would not take part in the 1984 Olympic Games in Los Angeles. It was the first of Moscow's allies to join the boycott.
In Washington, President Reagan said today he had 'a great feeling of disappointment' over the Soviet move.
To have participated at Los Angeles would have been tantamount to approving U.S. violations of the Olympic charter, the official news agency Tass said in the wake of the Soviet announcement Tuesday.
'Soviet sportsmen do not wish to be accomplices in the gross violations of the Olympic charter, which impair the international Olympic movement and subvert its noble ideals and principles,' the news agency said.
The Soviet action was prompted by 'its profound concern for the continued purity and unity of the international Olympic movement,' Tass said. In Rome, members of a team of 17 Soviet swimmers who have been training for the Olympics expressed regret over the boycott, but said they supported the decision.
'We have been training for these Olympics for many months and obviously to be told now that we cannot take part in them is not very pleasing, but we accept the decision of our government, ' said Sergei Fisenko.
'I would like to say that all the training and sacrifices we have had to endure will benefit us in other sporting meets,' Fisenko said.
'We are very disappointed not to be able to take part in the Los Angeles Olympics, but we agree with our government's decision,' said Yuri Mateev, one of the officials accompanying the team compete in an international meet in Rome.
A White House spokesman called the Soviet action 'totally unjustified.'
In Sydney, Australia, the coach of the touring Soviet Olympic skating team, Valery Kiselev, however said his country's boycott of the Los Angeles Olympics could be reversed.
'If the U.S. State Department guarantees the security of our sportsmen, then everything will be all right,' Kiselev said.
Although no official announcments were made by Soviet satellite countries, it appeared that many would follow Moscow's lead, with at least Poland and Czechoslovakia hinting they would not attend.
There was no comment from East Germany -- one of the Olympics' most successful medal-winning nations.
Influential Soviet journalist Victor Louis reported Tuesday the Kremlin already had drawn up plans for a communist bloc athletic meet to be held in Sofia, Bulgaria, in competition with the Los Angeles games, which begin July 28.
'Blueprints of the 'Red Olympics' are apparently already completed down to the last detail,' Louis wrote in London's Evening Standard newspaper. 'The Russians are believed to have decided on the move some time ago, probably when Konstantin Chernenko took over power in February.
'The alternative games would probably be announced at the last minute to throw the American (Olympics) organization into chaos,' Louis reported.
Interviewed on ABC-TV's 'Nightline' program Tuesday, Georgi Arbatov, head of the Soviet Union's U.S.A.-Canada Institute, said the Soviet action was taken because the lack of security at the games 'promised to create unbearable conditions' for the games.'
He acknowledged that poor U.S.-Soviet relations added to Moscow's concerns about the well-being of its sportsmen but denied the decision was taken in reprisal for President Carter's boycott of the 1980 Games in Moscow.
When the United States boycotted the 1980 Olympics to protest the Soviet invasion of Afghanistan, Carter encouraged allies to join the boycott. Sixty-four nations boycotted the event in whole or in part.
Poland said its participation in Los Angeles was 'under a question mark' and sources in Prague said they assumed Czechoslovakia would stand by Moscow and boycott Los Angeles as well.
Leonid Khomenkov, chairman of the Soviet Athletics Federation, hinted that other communist bloc nations would boycott the games.
At least one communist nation -- Yugoslavia -- said the Kremlin boycott would have no effect on its participation at Los Angeles. A spokesman for the Romanian Embassy in Vienna also said his country would take part.
Under Olympic rules, nations have until June 2 to state whether they will participate.
In its Tuesday announcement Tass said the International Olympic Committee had recognized Soviet complaints as just but nothing had been done to undo 'gross violations' of the Olympic charter.
Among the Russian points of contention were that the safety of the Soviet team could not be guaranteed and that the 'unbridled commercialization of the games had assumed ugly forms.'
Tass alleged the Reagan administration had continued to exploit the games for political purposes, and had connived at the whipping up of anti-Soviet hysteria.
It also said the 'arrogant hegemonistic course of the Washington administration is at odds with the noble ideals of the Olympic movement.'