Civil society organisations have joined opposition party calls for Parliament to reconvene for a special sitting to debate a motion of no confidence in President Jacob Zuma.

About 65 organisations wrote to National Assembly Speaker Baleka Mbete on Tuesday, asking for the sitting to be reconvened as a "matter of immediate priority" by Friday.

They included lobby groups, the Council for the Advancement of the South African Constitution, Right2Know, Teddy Bear Foundation, Dullah Omar Institute, Equal Education, Section27, and Ndifunukwazi.

"We are gravely concerned at the current state of South Africa's democracy and consider it of critical importance for the National Assembly to address this as an immediate priority," they said.

The Democratic Alliance, Economic Freedom Fighters, and United Democratic Movement have written to Mbete following Zuma's announcement on Thursday night that he was reshuffling the Cabinet. Finance minister Pravin Gordhan and his deputy Mcebisi Jonas were among those who lost their jobs.