Soviet leader Mikhail Gorbachev will meet with the leaders of Moscow's six Eastern European allies this month in a Warsaw Pact summit conference only weeks before his talks with President Reagan in Geneva, the Soviet and East European news agencies announced today.

The meeting will be held in Sofia, Bulgaria, the announcements said. Although no date was specified, western diplomats said they expected the meeting to be held sometime during the week beginning Oct. 21. The summit meeting will allow Gorbachev to consult with the leaders of pact members Poland, East Germany, Czechoslovakia, Hungary, Romania and Bulgaria, which serve as hosts to Moscow's intermediate-range nuclear missiles as well as about 565,000 Soviet troops. It may also allow East European leaders to test the new Soviet leader on questions of internal pact organization and policy, western diplomats said.

The conference may shortly precede or coincide with Reagan's proposed summit meeting with western leaders in New York Oct. 24. Reagan and Gorbachev are due to hold talks in Geneva Nov. 19 and 20.

However, the East Bloc summit has been called as a regular session not explicitly linked to the Reagan-Gorbachev meeting. Instead, it nominally represents the rescheduling of pact consultations to have been held in Sofia last January but postponed, apparently because of the failing health of Soviet leader Konstantin Chernenko.

"In accordance with a previous agreement, the political consultative committee of the Warsaw Treaty member states will hold its regular session in Sofia in the second half of October 1985," said the identically worded statements issued by official news agencies in Sofia, Warsaw and other capitals today.