During the visit, the two countries are expected to discuss expanding economic ties. A 2005 peace deal in oil-rich southern Sudan has sparked an investment boom in Africa's biggest country, and Turkish companies have already won large government construction contracts to build bridges and Sudan's first mall.

Bashir's government has come under fire over a separate, five-year conflict in Sudan's western region of Darfur, where the International Criminal Court is investigating Sudanese officials for war crimes.

The fighting has sparked what U.N. officials call the world's worst humanitarian crisis with an estimated 200,000 dead and 2.5 million driven from their homes.

"It's surprising that the Turkish government has chosen to honour a foreign leader responsible for massive human rights violations," Georgette Gagnon, Africa director at the New York-based rights group, said in a statement.

"The Turkish authorities should affirm their commitment to human rights principles by calling on Bashir to end the atrocities in Darfur," she said. Human Rights Watch said Bashir would receive a full military welcome in Turkey.

Turkey has itself come under scrutiny for curbs on freedom of speech and liberties while it tries to become a member of the European Union.

Sudan's government operates under Islamic sharia law while mainly-Muslim Turkey is fiercely secular. The election of the ruling AK party which has Islamist roots has caused tensions with the secular military establishment.