"It would be highly inappropriate for the Sudanese government, which is responsible for war crimes and crimes against humanity in Darfur, to preside over the African Union," said Peter Takirambudde, executive director of HRW's Africa division.
The 53 AU member states are expected to elect a new chairman during their summit scheduled to take place in the Sudanese capital, Khartoum, on 23-24 January. Bashir is a key candidate for the post, which is due to rotate to an east African country in 2006.
In a statement issued by foreign minister Lam Akol and published by the Sudan News Agency on Thursday, the Sudanese government said east African countries had unanimously decided to support Sudan for chairmanship of the AU.
The Sudanese government, allied militias and members of the country's rebel movements are currently under investigation by the International Criminal Court for violations of international law in the war-torn western Sudanese region of Darfur.
According to Takirambudde, "the AU's credibility, and its ability to promote and protect human rights, would be irreparably damaged" if Bashir is elected to head the organisation.
The Sudanese government was not immediately available for comment on the HRW statement.
The AU plays a critical role in Darfur, both by mediating between the parties in the conflict and by deploying peacekeeping forces with the mandate of monitoring the ceasefire agreement and protecting civilians.
The organisation's chairmanship has traditionally been handed to the country hosting the AU summit, but there is no formal obligation to do so. Observers note that the extension of the term of the current president, Nigerian head of state Olusegun Obasanjo, is an option.
Meanwhile, at a conference at the University of Khartoum on Thursday, women's organisations presented their concerns ahead of the AU summit.
"The coming into force of the AU Protocol on the Rights of Women in Africa on November 25, 2005 offers new possibilities for women and girls across the continent," Therese Nyondiko, representative of the Pan African Coalition Solidarity for African Women's Rights, said.
Nyondiko noted that the protocol recognised the rights of widows, elderly women, migrant women, marginalised women and women in detention, as well as reaffirming the rights of women to be free from gender-based violence in times of conflicts and to seek political office.
The conference urged the 36 African countries yet to ratify the protocol to do so, calling particularly on Sudan, as the summit's host, to do so while the AU meeting was in session.