Democratic Republic of Congo suspended former President Joseph Kabila's political party and ordered his assets seized over accusations of supporting Rwandan-backed rebels in the east, the government said.

The 53-year-old, who ruled from 2001-2019 and only stepped down after deadly protests against him, has said he wants to return to Congo to help seek a solution to the war.

But in statements late on Saturday, the interior ministry said his party was suspended for aiding the M23 rebels, while the justice ministry said his and other party leaders' assets would be seized after acts amounting to high treason.

Both statements said prosecutors had been instructed to initiate proceedings against him, but no details of the accusations were given.

There was no immediate response from Kabila.

Ferdinand Kambere, secretary of his Party for Reconstruction and Democracy, called the suspension a flagrant violation of Congo's constitution and laws in a statement to Reuters.

The M23 have taken two major cities in the mineral-rich east since the start of the year. The region has suffered decades of conflict rooted in the spillover from Rwanda's 1994 genocide and the struggle for control of minerals.

Kabila came to power after his father's assassination and refused to go when his final term expired in 2016.

He eventually agreed to step down and has lived in different African nations since.