BAKU, Azerbaijan (AP) — Authorities in Azerbaijan have arrested two opposition leaders in the capital for attempting to organize a procession, including the laying of flowers, at a national cemetery known as the Alley of Martyrs.

The Popular Front party said its leader, Ali Kerimli, and Jamil Hasanli, of the National Council of Democratic Forces, were taken into custody Saturday along with a group of supporters.

The site is used to honor those who died during Azerbaijan’s breakaway from the Soviet Union and in territorial disputes with neighboring Armenia.

The procession was organized by opposition leaders in honor of a national holiday on Saturday, known as the Day of National Revival. The holiday, created in 1992, commemorates Azerbaijan’s independence from the Soviet Union.

An opposition march through Baku was also planned.