A bomb exploded in a telephone booth close to the Communist Party headquarters in Warsaw, the first such incident since martial law was declared Dec. 13, Polish authorities reported Thursday.
Such attacks are rare in Poland. The last recorded bombing was of the Soviet airline offices in Warsaw shortly after the August 1980 labor revolt.
It seemed likely that the attack was linked with opposition to martial law, but the suspended Solidarity free trade union was not thought responsible. The union has preached passive resistance and warned its members against violence.