MOSCOW, SEPT. 4 -- Soviet President Mikhail Gorbachev moved today to relax Communist Party control over the armed forces and KGB secret police by ordering a major shake-up in the network of political cells in those organizations.

The Soviet news agency Tass reported that Gorbachev had signed a presidential decree providing for restructuring of the army and police cells to emphasize the principle of loyalty to the state rather than to the Communist Party. The security organizations have been under tight party control since the Soviet Union was founded seven decades ago.

Abolishing the system of political control the party has held over the security forces through the cells has been one of the main demands of political reformists here. They have argued that the system violates the principle of multi-party democracy and has made Communist Party membership virtually obligatory for senior army officers and KGB officers.

The presidential decree, however, is vague about what will replace the present system. In a series of speeches over the past few months, senior military leaders have strongly resisted proposals to permit multi-party politics in the armed forces or to depoliticize the army entirely.

The head of the main political administration of the armed forces was replaced shortly after the 28th Communist Party Congress in July, paving the way for a shake-up of the cells. His successor, Col. Gen. Nikolai Shlyaga, has acknowledged the need for reforms but has insisted that the Communist Party is the "only real political force with absolute authority in the army."

Under the present system, political officers are attached to every military unit from company level up and have the honorary rank of deputy commander. If the military leadership has its way, the political officers will continue to be responsible for ideological and cultural work.

The presidential decree said that the Defense Ministry, Interior Ministry and KGB have been given three months to draft new regulations for the political cells for official consideration.