Senior Zimbabwe opposition leader Tendai Biti has been arrested on allegations of inciting violence after the country's presidential elections, officials said on Wednesday.

The stage is set for an electoral battle on Thursday between NDA's Harivansh Narayan Singh and joint opposition candidate B.K. Hariprasad for the post of Rajya Sabha Deputy Chairman.

Congress MP B.K. Hariprasad was on Wednesday declared as the opposition candidate for the post of Rajya Sabha Deputy Chairman, election for which will be held on Thursday.

The contest for the post of Rajya Sabha Deputy Chairman is expected to be between a Congress nominee backed by other opposition parties and the candidate of the ruling BJP-led NDA as NCP on Tuesday decided against putting up a candidate for the August 9 election.

The ruling Biju Janata Dal (BJD) on Tuesday said both the NDA and the Opposition have sought its support for their candidates to the post of the Rajya Sabha Deputy Chairperson. The election is slated for Thursday.

The opposition is likely to field NCP member Vandana Chavan as its candidate for the Rajya Sabha Deputy Chairman's post in the August 9 poll. A final decision is expected to be taken later Tuesday.

The countdown to elect the new Rajya Sabha Deputy Chairman began here on Monday as Chairman M. Venkaiah Naidu announced the dates for the likely contest between the ruling NDA and a united opposition.

Trinamool Congress (TMC) leader Sougata Roy on Monday questioned the "neutrality" of EVM machines and said that 17 opposition parties are planning to represent to the Election Commission of India (ECI) and demand that EVMs should be scrapped and ballot papers should be brought back to ensure fair voting.

Opposition parties are set to contest the election to Rajya Sabha Deputy Chairman's post on August 9 and have decided to meet on Tuesday to finalise the candidate.

Janata Dal-United MP Harivansh is likely to be the NDA candidate for the Rajya Sabha Deputy Chairman election on August 9.