SOFIA, Bulgaria (AP) _ The interior minister and three other Cabinet members were relieved of their jobs on Thursday at a session of the National Assembly, the state news agency BTA reported.

The report gave no reason for the shake-up, which came one day after a Communist Party plenum and a series of changes in the ruling Politburo. However, Dimiter Stoyanov apparently left the Interior Ministry so he could assume even greater responsibility.

Stoyanov, 60, who holds the rank of colonel general, was appointed a full Politburo member and a party secretary - apparently responsible for security affairs - at the two-day party conference which ended Wednesday.

BTA said he was relieved of the interior minister's job he held since 1973.

Georgi Tanev, 45, named minister of transportation in September, became new interior minister. Tanev, a civilian, has been a member of the policy-setting Central Committee since 1981.

Western analysts, speaking on the condition of anonymity, speculated that Stoyanov's rise to the Politburo was linked to official criticism of growing lawlessness and a wave of criminal offenses in Bulgaria.

Replacing Tanev as transortation minister was Trifon Pashov, a regional party secretary for Mihailovgrad in northwestern Bulgaria.

Among other changes in the 14-member Cabinet, Health Minister Radoi Popivanov was replaced by Mincho Peichev, deputy chairman of the National Council of the Fatherland Front, a Communist-ruled mass organization.

Alexei Ivanov, the minister of agriculture and forestry, was replaced by Georgi Menov, a member of the standing committee of the Agrarian Party.

The official media has recently been criticizing the country's agriculture for output shortfalls, including shortages of such basic foodstuffs as potatoes, beans and rice.

In a speech to the party meeting Tuesday, national Communist leader Todor Zhivkov called for a reassessment of economic reforms. He said change so far has been inefficient and contradictory.

Zhivkov, 76, the longest-serving leader in the Soviet bloc, called for introduction of market-style competition in the economy, partly by turning state enterprises into share companies.

He made clear, however, that the state would maintain a controlling role.