U.N. Secretary General Ban Ki-moon is urging all parties in Thailand's Sunday election to act in a credible and fair manner and to “accept and respect the will of the people as expressed at the ballot box.”

In a statement issued in New York Wednesday, Mr. Ban said he is following the election closely and that he hopes it will be free of violence. He said a fair and credible election would contribute to the consolidation of democratic norms in the country.

Mr. Ban did not identify any particular concerns about Sunday's election, the first since political stresses flared into violence that killed more than 90 people a year ago. But international election observers and the nation's own media cite vote-buying as a regular feature of Thai elections.

Thailand's Election Commission is investigating dozens of complaints about the practice, while the Bangkok newspaper The Nation says the current price for a vote in the capital ranges from $16 to $65.

There are also concerns whether the Thai military would respect a victory by the front-running Puea Thai party, led by Yingluck Shinawatra. Her elder brother, former prime minister Thaksin Shinawatra, was ousted in a military coup in 2006 and now lives in exile to avoid being jailed on corruption charges.

Military commanders say they will remain neutral, but army chief General Prayuth Chan-ocha has urged the public to elect “good people” and defend the monarchy in what was widely seen as a veiled endorsement of the ruling Democrat party of Prime Minister Abhisit Vejjajiva.

Representatives from the Asian Network for Free Elections have been in Thailand since early this month to oversee the campaigns. About 60 ANFREL observers from 24 nations were on their way Thursday to remote parts of the country to monitor Sunday's voting.