SAN ANTONIO, Texas (Reuters) - A federal judge temporarily blocked key provisions of a Texas abortion law on Tuesday that required women seeking the procedure to undergo a sonogram and either view it or have a doctor describe the image.

The judge, in a victory for abortion rights activists, ruled there was cause to believe such a requirement was unconstitutional.

The judge in his preliminary injunction also struck down a provision of the law that would have called for the cancellation of a doctor's license for failure to comply.

(Reporting by Jim Forsyth, Writing by Cynthia Johnston, Editing by Alex Dobuzinskis)