The Israeli government, anticipating the return to Egypt of the remaining occupied portion of the Sinai peninsula in two years, plans to accelerate the construction of settlements in the southern part of the Gaza Strip.

Work has already begun on one new outpost, called Katif D, southwest of the town of Khan Yunis near the Rafiah Salient. Plans advanced by Agriculture Minister Ariel Sharon call for three more settlements to be built in the same region.

The purpose, government sources said, is to create a buffer between the Rafiah Salient, which will be returned to Egypt in March 1982, and the dense concentrations of Palestinians in the Gaza Strip. Sharon's plan envisions a new road network from the Negev Desert to provide direct access to the settlements from Israel.

Officials stressed, however, that there is no budget for the Gaza settlement plan and that implementation of it may be some time off. Israel also is experiencing difficulties finding volunteers to move into settlements in the occupied territories, partly as a result of Arab hostility.

Sharon was said to have urged a speedup in the south Gaza settlement program, first drawn in 1974, because he feels a strong Israeli presence is needed in the area before any agreement is made with Egypt on autonomy for the Gaza Arabs.

The plan, however, first disclosed in the Hebrew newspaper Haaretz, is certain to exacerbate tensions between Israel and Egypt, which already has suspended the negotiations on West Bank and Gaza Strip autonomy partly because of Israel Prime Minister Menachem Begin's settlement policy. Egypt captured the Gaza Strip in the 1948 war and occupied it until the 1967 Six-Day War.

Egyptian President Anwar Sadat has advocated an agreement on automony for Gaza first, which would then be used as a model for the West Bank. It appeared doubtful that disclosure of the settlement plans would give that idea much of a boost.

The Sharon plan was said to require the expropriation of about 2,800 acres of land, much of it sand dunes in the vicinity of Khan Yunis.

The chain of seven settlements would include a northern line of three existing outposts, Netzer Hazani, Katif and Ganei Tal and a line at right angle running south made up of three new outposts plus a nahal, or paramilitary settlement, at the southern edge.

Sharon's plan also calls for two new settlements in the northern Gaza Strip.

Peace Now, the main arm of Israel's antisettlement movement, today issued a statement condemning the Gaza plan, saying the government would waste millions of Israeli pounds "creating more Jewish ghettos."