HARARE, Sept 15 (Reuters) - Zimbabwean Prime Minister Morgan Tsvangirai, whose wedding plans appeared to have been thwarted when a court ruled he was already wed to a former flame, pressed ahead with his marriage on Saturday under a custom that permits polygamy.

The scandal - which had also seen another woman challenge his wedding plans - has gripped the nation and handed his rival, President Robert Mugabe, political ammunition as he seeks to extend his three-decade rule in an election expected within a year.

Tsvangirai could not be married in a legally recognised ceremony because of the embarrassing ruling. In an apparent bid to save face, he instead held a ceremony under Zimbabwe's "customary marriage" practice.

The 60-year-old and Elizabeth Macheka, 35, exchanged rings and promised to love each other. But there was no signing of a marriage certificate or vows of monogamy.

A magistrate said on Friday that Tsvangirai's former flame Locardia Karimatsenga had proved she was his wife under the customary marriage practice. A man can have several customary marriages, but if he has wed under the practice is precluded from holding a legal marriage ceremony.

Days earlier, another woman, South African Nosipho Regina Shilubane, also filed a court challenge to stop the wedding, saying she was engaged to the prime minister, with whom she said she had been romantically involved since 2009.

Tsvangirai on Saturday hosted a lavish reception party for hundreds of guests who had already gathered in Harare for his wedding, but Mugabe and several other heads of states invited from region did not turn up.

The ceremony, at a Harare garden venue, was presided over by a priest. Tsvangirai wore a black business suit and Macheka a flowing white gown, and they smiled and waved at the guests.

The prime minister's aides said he intended to have just one wife.

The case has fanned tabloid-style headlines and aired salacious details about Tsvangirai's private life since the death of his wife Susan in a car crash in 2009.

While 88-year-old President Mugabe has been criticised for ruining what was once one of Africa's strongest economies, Tsvangirai is now facing public questions about his judgment.

Tsvangirai's spokesman dismissed both court cases against him as plots by the former British colony's security services to tarnish the reputation of a man who has fought hard to end Mugabe's rule.

(Reporting By Cris Chinaka; Editing by Pravin Char)

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  • Zimbabwean Prime Minister Morgan Tsvangirai, left, is seen with his wife Elizabeth Macheka during a traditional wedding ceremony in Harare, Saturday, Sept. 15, 2012, despite a court ruling that canceled his marriage license on allegations that he would be committing bigamy. (AP Photo/Tsvangirayi Mukwazhi)

  • Zimbabwean Prime Minister Morgan Tsvangirai, left, is seen with his wife Elizabeth Macheka during a traditional wedding ceremony in Harare, Saturday, Sept. 15, 2012, despite a court ruling that canceled his marriage license on allegations that he would be committing bigamy. (AP Photo/Tsvangirayi Mukwazhi)

  • Zimbabwean Prime Minister Morgan Tsvangirai, left, is seen with his wife Elizabeth Macheka during a traditional wedding ceremony in Harare, Saturday, Sept. 15, 2012, despite a court ruling that canceled his marriage license on allegations that he would be committing bigamy. (AP Photo/Tsvangirayi Mukwazhi)

  • Zimbabwe Prime Minister Morgan Tsvangirai holds hands with his wife Elizabeth Macheka after exchanging vows at a customary law ceremony during their wedding held in Harare, on September 15, 2012. (JEKESAI NJIKIZANA/AFP/GettyImages)

  • Zimbabwe Prime Minister Morgan Tsvangirai (R) kisses his wife Elizabeth Macheka (L) after exchanging vows at a customary law ceremony during their wedding held in Harare, on September 15, 2012. (JEKESAI NJIKIZANA/AFP/GettyImages)

  • Zimbabwean Priminster Morgan Tsvangirai, left, is seen with his wife Elizabeth Macheka during a traditional wedding ceremony in Harare, Saturday, Sept. 15, 2012, despite a court ruling that canceled his marriage license on allegations that he would be committing bigamy. (AP Photo/Tsvangirayi Mukwazhi)

  • Zimbabwean Prime Minister Morgan Tsvangirai is seen during a traditional wedding celebration in Harare, Saturday, Sept. 15, 2012, despite a court ruling that cancelled his marriage license on allegations that he would be committing bigamy. (AP Photo/Tsvangirayi Mukwazhi)