Caracas (AFP) - Venezuela's opposition urged the international community Wednesday to prevent what it alleged was an attempt by President Nicolas Maduro to mount a "judicial coup."

The plea came after Maduro's party filed a legal challenge to his opponents' landslide victory in legislative elections.

In an open letter to UN Secretary General Ban Ki-moon and senior international officials, the opposition Democratic Unity Roundtable (MUD) coalition condemned the legal threat to the super-majority it won on December 6.

"The country, the region and the world are facing a judicial coup attempt against the Venezuelan people's decision," MUD executive secretary Jesus Torrealba wrote.

"The ruling party's irresponsible behavior is pushing the entire country to the brink of disaster, which would have grave consequences for the entire region."

The letter was also addressed to European Union foreign affairs chief Federica Mogherini and senior officials of the Organization of American States, the Union of South American Nations and regional bloc MERCOSUR.

The opposition won 112 of 167 seats in the elections, a dramatic blow to Maduro and the "revolution" launched in 1999 by his late predecessor Hugo Chavez.

But the United Socialist Party of Venezuela (PSUV) has filed court challenges contesting the election of nine lawmakers.

- The people's will -

The suits could reduce the opposition's seats to 103 -- just shy of a two-thirds majority -- when the new National Assembly is inaugurated on January 5.

The super-majority gives MUD the power to put legislation to a referendum, remove officials from office, call an assembly to draft a new constitution and possibly seek to force Maduro from power before the end of his term in 2019.

Maduro alleged Tuesday that the vote was marred by fraud.

"Criminals were buying votes ... There was a plan," he said on state TV, adding that authorities were investigating.

The legal challenge will be decided by the Supreme Court of Justice.

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On Wednesday, the nine opposition politicians involved responded by filing a motion urging the judges in the case to recuse themselves because of close ties to the PSUV.

"We hold the president responsible for whatever happens if (the PSUV) continues with its plan to ignore the people's will," said Simon Calzadilla, one of the nine.

Last week, the PSUV used an extraordinary session in the final days of its legislative majority to name 13 new judges and 21 substitute judges to the 32-member high court.

The opposition, which boycotted the session, condemned the move.

Analysts warn of a tough political struggle ahead for oil-rich but deeply troubled Venezuela, which is mired in recession and facing a potentially chaotic period of divided government.