A senior Communist Party official warned that the proliferation at factories of underground units of the banned Solidarity trade union could jeopardize planned round-table talks aimed at ending Poland's economic crisis.

In Gdansk, Solidarity leader Lech Walesa insisted Thursday that his organization wants speedy re-legalization but does not seek a share of political power.Walesa, who called off a nationwide wave of strikes Sept. 3, has met three times this month with Interior Minister Czeslaw Kiszczak and Stanislaw Ciosek, a member of the party's ruling Politburo.

Walesa was promised during the meetings that the legalization of Solidarity will be discussed next month during round-table discussions among representatives of the government, the outlawed union, the Roman Catholic Church and other sectors of Polish society.

Dozens of Solidarity founding committees have sprung up at plants around the country on the apparent premise that the government's willingness to talk with Walesa represents a de facto recognition of the trade union, whose establishment in 1980 at the Lenin shipyard in Gdansk propelled the charismatic electrician to international fame.