KYIV (Reuters) - Belarusian police searched the offices and homes of journalists and human rights activists for the third successive day on Friday, extending what rights activists say is a new crackdown on opponents of President Alexander Lukashenko.

       The Poland-based Nexta Live channel said the office of U.S. broadcaster Radio Liberty in the capital Minsk was among those raided. Belarusian human rights organisation Viasna-96 reported that two Radio Liberty journalists had been detained.

       Belarusian security officials were not immediately available for comment.

       The authorities have shut down a number of non-state media outlets and human rights groups since protests began last August against a presidential election which the opposition say was rigged. Lukashenko, in power since 1994, denies electoral fraud.

       Police officers went on Friday to the homes of a journalist from Polish TV channel Belsat and those of several local reporters, Viasna-96 reported.

       On Wednesday and Thursday, security officials conducted searches in around 20 human rights, charitable, media and expert institutions, detaining more than 15 people, including the head of Viasna-96.

       The searches and detentions in the former Soviet republic have been condemned by Western politicians, international human rights activists and Belarusian protest leader Sviatlana Tsikhanouskaya, who is based in Lithuania.

       British Foreign Secretary Dominic Raab has said Britain condemns an "escalation in repression" in Belarus, and the European Union and United States have imposed sanctions on Belarus in recent months.

       (Writing by Pavel Polityuk, Editing by Timothy Heritage)