The main Syrian Kurdish group declared a federal region on Thursday in Kurdish-controlled areas in northern Syria, a move that was immediately rejected by both the government and opposition.

Nawaf Khalil, an official with the Democratic Union Party, or PYD, told The Associated Press that the announcement was made at a conference being held in the town of Rmeilan in the northeastern province of Hassakeh.

The move was rejected by the Syrian Foreign Ministry describing it as "unconstitutional and worthless." It warned against any attempt to encroach upon the integrity of Syrian territory.

The Syrian National Coalition, one of the main Syrian opposition groups, also said it rejects such unilateral declarations and warned of any attempt to form autonomous regions that, "confiscate the will of the Syrian people."

Khalil said participants in the Rmeilan meeting have approved a "democratic federal system for Rojava-Northern Syria." Rojava is a Kurdish word that refers to three distinct enclaves, or cantons, under Kurdish control in northern Syria: Jazira, Kobani and Afrin.

Khalil said participants who include Turkmen, Arabs, Christian and Kurds in northern Syria said after they approved the draft that they are now preparing a final statement that will be read later Thursday.

"Federal and Democratic Syria is a guarantee of coexistence and brotherly relations between people," read a banner posted online from inside the room of the Rmeilan conference.

Salih Muslim, the co-president of the PYD, said by telephone that those meeting "are setting up the basis on how constituencies will deal with each other."

Meanwhile in Moscow, the commander of the Russian Air Force said the withdrawal of the bulk of the Russian forces from Syria should be complete in two to three days.

Col. Gen. Viktor Bondarev said in an interview with the Komsomolskaya Pravda daily on Thursday that the Air Force aims to meet President Vladimir Putin's deadline and pull out in the next two to three days.

Putin on Monday announced the withdrawal of most of the Russian forces from Syria to end a five-and-a-half-month campaign there. The first group of bombers left for Russia on Tuesday. Moscow didn't specify how many aircraft and troops would be withdrawn. It has not revealed how many soldiers it has deployed to Syria, but U.S. estimates of the number of Russian military personnel vary from 3,000 to 6,000.