Democratic Republic of Congo Prime Minister Sylvestre Ilunga threatened his government’s resignation after the justice minister was briefly arrested in a dispute about a proposed law that could affect the independence of the country’s judicial system.

Justice Minister Celestin Tunda Ya Kasende was detained by police on Saturday and released after questioning. Tunda is an ally of Ilunga and former President Joseph Kabila and is in a coalition government with supporters of current President Felix Tshisekedi. Kabila’s allies control most of the government’s ministries and both chambers of parliament.

“This serious and unprecedented incident is of a nature that will weaken the stability and the harmonious functioning of institutions, and provoke the government’s resignation,” Ilunga said in a statement published on his office’s website on Sunday.

Congo’s parliament is considering a proposal that could give the justice ministry more oversight over the country’s judiciary. The measure has led to demonstrations by Tshisekedi’s supporters and was criticized last week in a joint statement by the U.S., U.K., and Canadian embassies as having the potential “to undermine an independent judiciary.”

Tshisekedi’s spokesman declined to comment on the minister’s detention.