Members of Poland's outlawed Solidarity labor union have formed a new underground group, calling for East European countries to unite and rebel against Soviet domination. An eight-page statement signed by the "Polish Independence Committee" said the Soviet system is going through a crisis and urged East European nations to take advantage of this opportunity. "We must revolt. Nobody can do it for us," the statement said, without specifying what form the revolt should take. A spokesman for the group said a copy of the statement was given to Vice President George Bush during his four-day visit to Poland last week. The group was created in September and includes Solidarity activists, he added, but he did not say if Solidarity founder Lech Walesa is a member.