Supporters of Mikhail Gorbachev, the last leader of the Soviet Union, have dubbed him Russia's first political "refusenik" after he was banned from leaving the country for failing to answer a court summons.


The ban was imposed Friday at the request of Russia's Constitutional Court after Gorbachev failed for a second time to respond to a summons requiring him to testify at the trial of the former Communist Party.


The court's decision, agreed and enforced according to Itar-Tass by Russia's foreign and security ministries, has caused Gorbachev to cancel a trip to South Korea, where he was scheduled to arrive for a four-day visit on Wednesday.


Gorbachev met the South Korean ambassador in Moscow to express his regrets, but promised to go to Seoul soon.


In a press release, the Gorbachev Foundation called Gorbachev "Russia's first political 'refusenik'". The reference served to compare him to Soviet Jews who in the 1970s and '80s were denied exit visas to leave Russia for Israel.


"This action could be seen as administrative arbitrariness that


could lead to the resumption of limiting rights for political motives", according to the press release. Gorbachev, it continued, was "the first victim of this arbitrariness".


The architect of perestroika has repeatedly said he would not testify in the case, on one occasion warning that he would say nothing "even if handcuffed", and on another that "I will not be the hero of this comedy".


He described as "political" the proceedings, in which the court is judging both the constitutionality of Boris Yeltsin's decision to ban the Communist Party and the constitutionality of the party itself.


The court chairman, Valery Zorkin, called those remarks "insulting".


Speaking on television Saturday night, Russia's justice minister, Nikolai Fedorov asked Gorbachev to "fulfill his constitutional and civic duty".


Gorbachev and his former aide, Valentin Falin, are the only two of 11 former Party leaders summoned so far who have refused to testify at the hearings.


The former Soviet prime minister, Nikolai Ryzhkov, appeared in court on Thursday and attacked Gorbachev for his refusal. The former ideology chief, Yegor Ligachev, is due to appear on Monday.