BRATISLAVA, Nov 6 (Reuters) - Slovakian President Zuzana Caputova on Wednesday vetoed a new law extending a ban on publishing opinion polls up to 50 days before elections and vowed to challenge it at the Constitutional Court if the parliament overturns her veto.

The bill, approved by parliament last week, makes the moratorium on polls third longest in the world after Cameroon and Tunisia, the Slovak Academy of Sciences has said, extending it from a 14-day blackout.

The bill was adopted ahead of an election due on Feb.

29 next year, and was adopted with the votes of the ruling leftist Smer party, junior coalition Slovak National Party (SNS) and the opposition far-right People's Party-Our Slovakia.

"I believe the law violates the right to information granted by the Constitution and it limits political competition," Caputova told reporters.

"If the parliament overturns my veto, I will use my right to appeal it at the Constitutional Court and ask the court to put it taking effect on hold," until a final ruling.

The presidential veto can be overturned with 76 votes, a simple majority in the 150-member chamber.

The bill's authors, from Smer and SNS, said they aimed to protect voters from disinformation so they could base their decisions on the parties' programmes and activities.

The bill, however, does not ban parties from procuring their own opinion polls, as long as they keep the information out of the public domain.

It has drawn strong criticism from opposition parties and 유로247가입코드 political experts who view it as an attempt to disadvantage challengers from new parties.

Slovakia, like other countries in Europe, has seen a rise in new parties in recent ye

r />Newcomer activist lawyer Caputova herself defeated Smer's candidate in a presidential runoff in March after a late surge in support.

The socially conservative Smer party, in power nearly continuously since 2006, remains the favourite for next year's election despite having suffered several electoral defeats since the 2018 murder of an investigative journalist Jan Kuciak and his fiancee, that sparked mass protests and ousted then Prime Minister Robert Fico from office.

The long blackout on polls is the second amendment to election rules this year.

In June, the government rushed through a limit on private donations to political parties, which opponents said favoured established parties receiving state funding based on votes they won in past electi

r />(Reporting by Tatiana Jancarikova; Editing by Alison Williams)