The United Nations is facing a chorus of criticism over the inauguration as president of its general assembly of Uganda's foreign minister, just four months after that country enforced a brutal and widely denounced anti-gay law.

Sam Kutesa will become ceremonial head of the world parliament on 11 June. There will be no ballots cast and he will be "elected by acclamation", as he is the only candidate for the 12-month post, having been chosen by t he African Union for the job that falls this year to Africa on a Buggins' turn basis.

But as the appointment nears, questions are being asked about his track record of alleged corruption, as well as his role as cabinet member of a government that has enacted one of the most virulent homophobic laws on the globe. Voices of disapproval have spread from Uganda to the general assembly's home in New York and to the US senate.

New York senator Kirsten Gillibrand said: "It would be disturbing to see the foreign minister of a country that passed an unjust, harsh and discriminatory law based on sexual orientation preside over the UN general assembly." In the UK the rights campaigner Peter Tatchell has called on the government to intervene. "David Cameron and William Hague should be lobbying the UN to block Kutesa's appointment on the grounds that his political record is inconsistent with UN principles," he said.

Uganda's president, Yoweri Museveni, signed the anti-homosexuality act in February. It builds on an existing ban on homosexuality dating back to British colonial times and authorises life imprisonment for "repeat homosexuals" – couples in a committed relationship; seven-year sentences for anyone helping gay people to avoid detection; and five years in prison for "promotion of homosexuality".

Kutesa, as Uganda's foreign affairs chief, was responsible for defending the law in the face of international condemnation. Though less virulent in his advocacy than Museveni – who has called gay people "disgusting" – Kutesa said "the majority of Africans abhor this practice". He added that "we shall not accept promotion and exhibition, because we think that is wrong for our young people and it offends our culture".

His new role as president of the UN general assembly will be largely figurative. He will chair meetings of the assembly – including the annual shindig of all 193 nations in New York in September that will be addressed by President Obama, Cameron and other world leaders – but in other respects his influence will be limited.

Nonetheless, the elevation of such a controversial figure to such a prevalent seat in the world body is disconcerting to a growing number. "There are real concerns about Sam Kutesa's commitment to the values embodied in the Universal Declaration of Human Rights, including his defence of Uganda's profoundly discriminatory anti-homosexuality law," said Maria Burnett, an expert on Africa at Human Rights Watch.

A Change.org petition calling on the Obama administration to revoke Kutesa's visa to enter the US and thus prevent him taking up the presidency has attracted almost 3,000 signatures. It was written by a Ugandan, Milton Allimadi, who edits the New York-based site Black Star News. Allimadi said that Kutesa represented "the very antithesis of what the UN is supposed to embody globally – peace, security and human rights for everyone".

Asked recently what he thought about the petition, Kutesa said: "I'm not bothered by that, because it's incorrect. It's a lie."

The Ugandan mission to the UN in New York said there was no one available for comment.

In addition to the gay issue, Kutesa has also been criticised for persistent allegations of corruption. A lawyer by training, he is extremely wealthy and owns several luxury properties in Kampala. In 1999 he was censured by the Ugandan parliament for alleged misuse of his office. In 2009 he was named in a confidential US diplomatic cable disclosed by WikiLeaks as one of three senior government ministers Museveni had failed to hold "accountable for corruption allegations". Two years later he was forced to step down as minister after he and two other cabinet members were accused in parliament of accepting bribes from a foreign oil company – he was reinstated in 2012, but only after the investigation into the three was quashed by court order.

Cissy Kagaba of the Anti-Corruption Coalition Uganda in Kampala said that Kutesa's elevation to such a prominent UN role was sending the wrong message: "It says that people who have been linked to alleged corruption can still represent their country, and that will make the fight against it much more difficult."