The Soviet Union informed the Japanese government last night that it will soon deliver certain unidentified documents and materials that its search parties have discovered in the Sea of Japan in the area in which a South Korean airliner was shot down by a Soviet plane Sept. 1.

The Soviets have refused to permit Japanese search parties to enter Soviet waters or airspace to take part in the search.

Soviet Ambassador Vladimir Pavlov told the Japanese Foreign Ministry last night that fragments of the missing plane were found at four places, north and west of tiny Moneron Island. The ambassador did not elaborate on that information.

Pavlov also told the Japanese that the Soviet Union would soon announce the results of the search in accordance with international practices.

The Japanese government today announced modest sanctions against the Soviet national airline, Aeroflot, including a ban on landing of charter flights in Japan.

The government also appealed to the Japanese people to abstain from using Aeroflot, and instructed public officials, both national and local, not to use the Soviet carrier.

The government announcement also said that it will not approve applications for additional Aeroflot flights to and from Japan.

The Japanese response did not affect any regularly scheduled Aeroflot flights.