The Kuwaiti defense minister said today this conservative Moslem sheikdom has signed its first arms deal with the Soviet Union, a Kuwaiti newspaper reported.

Sheik Saad Abullah Sabah, who also is interior minister, told the newspaper Al Rai that Kuwait bought "certain sophisticated weapons." He gave no details.

The leftist weekly Al Hadaf reported here last week that the purchase included Soviet SAM-7 surface-to-air missiles, effective against low-flying aircraft.

Kuwait also has expressed a desire to buy Soviet artillery and tanks and these negotiations are continuing the weekly added.Press reports have also said Kuwait would develop a naval base on the island of Faylaq, with construction carried out by Japan.

Sheikh Saad said Kuwait was diversifying its weapon sources but was still cooperating with its traditional suppliers in Europe and the United States. Kuwait is carrying out a $2.7 billion five-year plan to expand and modernize its armed forces.

In other Middle East developments:

More than 100 families fleeing the fighting in southern Lebanon arrived in Sidon and nearby areas, saying rightists were closing in on the village of Aytaroun, a Palestinian-leftist stronghold near villages along the border with Israel.

In Tel Aviv, former Defense Minister Moshe Dayan announced that he will stand for Israel's governing Labor party in next month's parliamentary elections. He met earlier with Prime Minister Yitzhak Rabin. Dayan had threatened to join the Likud opposition if his demand was not met for a commitment from Rabin on the holding of new elections before any territorial concessions were made on the occupied West Bank of the Jordan.

Dayan said he had received a letter in which Rabin said he "does not object in principle" to new elections before any granting of territorial concessions.