Moscow, under an umbrella of anti-US charges, admitted Tuesday to having ''stopped the flight'' of a Korean Air Lines jumbo jet last week. A formal government statement read out on the evening television news repeated Soviet statements the plane was evidently on a United States spy mission and had failed to respond to signals from Soviet military jets sent aloft to interrogate it. The statement also repeated Soviet charges the USwas ultimately to blame for the disaster.
''The anti-aircraft defenses fulfilled the order of the command post to stop the (Korean Air Lines) flight,'' the statement said. It added, ''Such actions are fully in keeping'' with Soviet border law and that ''the Soviet pilots, in stopping the actions of the intruder plane, could not know it was a civilian aircraft.''
Successive Soviet news media and official comments since the loss of the airliner have stopped short of any indication Soviet fighters had downed the plane. The initial Kremlin response was to say fighter jetshad scrambled merely to ''assist'' the Boeing plane. Further statements added that the Soviets had fired tracer shells to alert the airliner's crew.
The government statement followed indications that Moscow, beneath its barrage of anti-US allegations concerning the air disaster, was increasingly concerned over the effects of the crisis.
At the same time, both the statement and a Pravda article Tuesday made it clear the Kremlin remained intent on resisting overseas pressure for acknowledgment of blame.
Tuesday's Pravda made the first mention in the Kremlin media of Western charges the Soviets shot down the plane. Diplomats here see this as a sign of concern to counter foreign radio reports on the dispute.
The Pravda piece includes an apparent bid to limit effects at home of reported pilot voice transcripts at variance with the Kremlin version of the air tragedy.
A transcript cited by President Reagan in an address Monday night contradicts Soviet contentions the Boeing was flying without lights. The transcript records a Soviet fighter pilot's remark, only minutes before the jumbo went down, that the ''target'' was flashing its navigation lights. This is an international signal that an aircraft is agreeing to obey directions of nearby military jets.
The Pravda article remarked: ''At present the masterminds of this (spy) provocation are trying to foul the trail.
''Without denying the fact of violation of Soviet air space by the South Korean plane, they are putting forward the version that the plane went off course because of technical trouble and was shot down by a Soviet fighter. To support this version they refer to some 'truncated' record of radio exchanges between the Soviet planes and their ground control. But facts give different evidence.''
The flight, Pravda said, ''was evidently calculated to test . . . the possibility of making unhindered reconnaissance flights over Soviet territory under cover of civilian planes. . . .''
The Soviet media, meanwhile, withheld detailed comment on retaliatory sanctions by the US and Canada. Canada banned the Soviet airline Aeroflot from landing for 60 days. The US reaffirmed a similar ban in effect since martial law began in Poland.