The State Department has recommended about $1.2 billion in military sales to Saudi Arabia in a new phase of the modernization program for that country's National Guard, departmental officials said yesterday.

If President Carter gives his approval and Congress goes along, the Saudis will receive tanks and a wide range of arms and gear for the improvement of four National Guard mechanized battalions.

Another four battalions have been undergoing modernization in a joint U.S.-Saudi program since 1973, according to State Department spokesman Hodding Carter. The United States agreeded in the spring of last year to look into the possibility of reequipping the additional batalions, Carter said.

Carter rejected suggestions that the sale of additional arms to the world's largest oil exporter might be linked to the recently announced increase in Saudi oil production. "U.S. arms sales have been conducted without any regard or links to Saudi positions on oil," the spokesman said.

The Saudis, after urging by the United States, recently agreed to increase their oil production about 1 million barrels per day for a temporary period. The production increase is expected to have an important effect on the tight and recently chaotic international petroleum market.

A 14-member Pentagon survey group, headed by Maj. Gen. Richard D. Lawrence, was in Saudi Arabia from March to June to confer with military leaders there.