Zimbabwe‘s President Robert Mugabe, arguably Africa’s most outspoken opponent on gay rights, is seeking re-election for the seventh time and human rights groups warn the contest is being rigged.

Amnesty International and Human Rights Watch have reported incidents of large-scale intimidation as long queues form at polling stations throughout Zimbabwe.

Prime Minister Morgan Tsvangirai’s Movement for Democratic Change (MDC) has accused Zanu-PF of doctoring the electoral roll, a charge it has denied.

Fresh suspicions of vote rigging were sparked by a Research and Advocacy Unit study which said the electoral roll includes one million dead voters or people who have emigrated.

Mugabe, 89, has been ramping up the homophobic rhetoric in the run-up to Wednesday’s poll.

Last Tuesday, he reportedly urged for the heads of gay men to be chopped off and said gay people were worse than “pigs, goats and birds”.

“If you take men and lock them in a house for five years and tell them to come up with two children and they fail to do that, then we will chop off their heads,” Mugabe told Zanu-PF supporters in Mutare.

Criticising US President Barack Obama for linking foreign aid to the protection of gay rights, Mugabe added: “Obama this man born of an African father and a white mother told us that US can only provide financial aid if we accepted homosexuality as a country.”

Days later Mugabe denounced Archbishop Desmond Tutu for speaking in support of LGBT rights, saying Zimbabwe will “Never, never, never” support homosexuality.

Zimbabwe’s economic problems have seen millions leave the country to find work in recent years.

Violence marred the last election in 2008, with Morgan Tsvangirai pulling out of a second round run-off against Mugabe after 200 of his supporters were killed.

The African Union and the Southern African Development Community have both sent observers to monitor this year’s elections.

Casting his vote in Harare, Mr Tsvangirai predicted his MDF party would win “quite resoundingly” and called it a “historic moment”.

In March, campaign group Gay and Lesbian of Zimbabwe (GALZ) criticised Mr Tsvangirai for denouncing homosexuality and reportedly saying marriage “should be between a man and a woman.”

Male same-sex sexual activity is illegal in Zimbabwe and since 1995 the government has carried out campaigns against gay men and lesbians.

Mugabe, president since 1987, is seeking his seventh term in office.

He marked his 88th birthday in February 2012 by urging gay people to go to “hell” in a public speech.