Lawmakers in Democratic Republic of Congo have introduced a bill to restrict the presidency to people with two Congolese parents, a move critics said on Friday aimed to block a millionaire businessman from challenging the president in the 2023 election.

The bill, championed by an ally of President Felix Tshisekedi, was introduced to parliament on Thursday, with supporters saying it seeks to safeguard the African nation's sovereignty and prevent foreign meddling.

Opponents say it undermines the rights of Congolese citizens with immigrant parents and sought to exclude Moise Katumbi, a millionaire businessman and former regional governor who is expected to run in 2023. Katumbi's father was Greek.

"It is clearly a manoeuvre by those who want to hold onto power," Olivier Kamitatu, Katumbi's spokesperson, told Reuters.

"We are treading on the red line," he said, adding that the bill had to be scrapped or Katumbi's party would withdraw from the Sacred Union, a coalition formed by Tshisekedi last year.

Tshisekedi's spokesperson, Kasongo Mwema, said the president had "already excoriated these types of divisive subjects" but said he did not know whether Tshisekedi would veto the bill.

Critics dubbed the bill the "congolité" law, echoing the term "ivoirité" which was used in the Ivory Coast during a period of increasingly ethnically-driven politics that led to civil wars in 2002 and 2010.

Congo also has a history of conflicts, often tinged by political and ethnic rivalries in the vast country that is rich in raw materials, including a 1998-2003 war during which millions died.

The UN peacekeeping mission head in Congo, Bintou Keita, urged world powers not to let Congo slip back into divisive politics.

"I underscore the necessity of organising inclusive and peaceful elections while paying attention to the potentially dangerous consequences of a divisive debate about nationality," she told the UN Security Council on Wednesday.

Responding on Twitter, the bill's main champion, Noel Tshiani, told the United Nations to stay out of the issue.