Egypt today ordered Soviet Ambassador Vladimir Polyakov, six other embassy personnel and two Soviet correspondents to leave the country within 48 hours because of their alleged involvement in a plot to foment sectarian strife in the country.

A statement issued by the official news agency following a cabinet meeting also said the government was closing down the Soviet military liaison office in Cairo and canceling the contracts of the estimated 1,500 Soviet advisors still working here, almost all of whom are civilians.

In addition, the statement said Egypt was demanding that the size of the Soviet Embassy be reduced to that of Egypt's mission in Moscow, which presently has a staff of about 10. Egypt said it is also closing its military liaison office in the Soviet Union.

The measures, which appear to fall just short of a total break in relations, followed a speech by President Anwar Sadat Monday that accused the Soviets of promoting a rift between Christians and Moslems in Egypt with the aim of inciting violence and bringing down Sadat'sregime.

The statement issued today accused Moscow of recruiting agents in Egypt and exploiting religious strife as well as "influencing the spread and escalation of the sectarian conflict." It charged the Soviets acted in coordination with leftist elements here and unnamed Arab countries hostile to Egypt.

The Soviets, the statement said, tried to "cause troubles on the internal front, distort democracy and incite sedition and conflicts among Egyptians" through the activities of the Soviet intelligence services and the Soviet Embassy here.

Ambassador Polyakov was called to the Foreign Ministry and told he was being declared persona non grata for having "suspicious contacts" with Egyptians active in fomenting the sectarian violence, which has taken over 20 lives and wounded more than 100 in the past three months.

On Sept. 3, the government arrested more than 1,500 religious militants and opposition elements in the most sweeping crackdown on sectarian strife and political activity since Sadat came to power 11 years ago this month.

The government also announced that one member of the Hungarian Embassy "involved in the Soviet plot against Egypt" was being expelled with the Soviet ambassador and his six aides. The correspondents named worked for the official Soviet Tass news agency and a newspaper, Trud.

The Soviet Embassy tonight had no comment on the expulsions.

Press reports over the past two days have charged that the Soviets worked with various domestic opposition groups, including one headed by former deputy prime minister Mohammed Abdel Salem al Zayyat that used the code name "Swamp." Zayyat was alleged to have held secret meetings with Soviet intelligence officiers, and the Cairo newspaper Mayo Monday published pictures of Zayyat and his sister, Latifa, entering the grounds of the Soviet Embassy here.

The group led by Zayyat was said to include followers of former pro-Soviet president Gamal Abdel Nasser, Communists and members of the National Progressive Union Party, and was alleged to have made contacts with members of the Moslem Brotherhood and extremist Islamic groups to hide its "true colors" and deceive the Egyptian people.

In his speech, Sadat said the Soviets had decided to work with the Moslem fundamentalists because the Socialists and leftists were too weak. Sadat said: "So they figure out they could get them the militants and the government into a confrontation through religious strife and the scene would be free for them to take over."

Despite his strong attack on the Soviets, Sadat gave no hint during his speech that the government was about to take the measures it announced today.

The local media reported Egyptian intelligence had worked for three years in surveillance of the "Swamp" group and had recorded its comings and goings to Moscow as well as its activities and contacts with the Soviet Embassy in Cairo.

Another Egyptian intelligence operation bearing the code name "Sea" was said to involve an Egyptian Christian studying for a doctorate in Moscow, whom Soviet agents tried to recruit. The student reportedly responded by informing on the agents.

The latest diplomatic list of embassies and their personnel indicates the Soviets have 41 diplomats and other staff stationed here. If this is the case, then another 24 would have to leave to meet the Egyptian demand for the size reduction of the Soviet staff.