Forty-four members of Congress yesterday introduced a bill calling for extensive new sanctions against South Africa, including a ban on new U.S. investments, that would be lifted if the white government there releases all black political prisoners and begins "good-faith negotiations" to end apartheid.

The bill, whose chief sponsors are Edward M. Kennedy (D-Mass.) and Lowell P. Weicker Jr. (R-Conn.) in the Senate and William H. Gray III (D-Pa.) in the House, would go considerably further than the sanctions imposed by President Reagan last September.

The legislation would include not only an end to U.S. investments but a ban on landing rights for South African aircraft here and a prohibition on importing South African coal, uranium and steel.

In addition, if South Africa did not free within one year its black political prisoners, most notably the head of the African National Congress, Nelson Mandela, the bill would require U.S. computer companies to withdraw from South Africa and would ban computer exports to that country.

At a news conference, Kennedy said the proposed legislation is a response to the recent call by Bishop Desmond M. Tutu, the South African black Nobel Peace Prize laureate, for the world community to apply "punitive sanctions" on South Africa in an effort to force an end to apartheid.

Kennedy and other members of Congress at the news conference cited the worsening racial violence inside South Africa, marked by the rise in the average monthly death toll among blacks from 70 last year to 130 now, and the South African raids Monday on black nationalist sites in three neighboring states.

Gray said these developments showed there had been "no meaningful reform" in the apartheid system over the past year and that it is not only an internal racial problem but "a threat to regional peace."

The sanctions bill is being introduced in the House by 20 Democrats and 10 Republicans, including a conservative, Rep. Vin Weber (R-Minn.), and in the Senate by 13 Democrats and one Republican, Weicker.

The proposed sanctions would go far beyond the measures Reagan imposed Sept. 9. They ended U.S. bank loans to the South African government, stopped computer sales to apartheid-enforcing agencies and banned the sale of South African krugerrands in the United States.

The proposed legislation is also stronger than a 1985 House-approved bill, which does not include a ban on landing rights for South African aircraft, a prohibition on imports of coal, uranium and steel or any provision for the disinvestment of U.S. computer firms.

The proposed ban on aircraft would end the five flights a week by South African Airways between Johannesburg and New York.

Ending imports of the three materials would strike at a main source of foreign exchange for South Africa, though U.S. imports of them are relatively small. Annual South African uranium exports to the United States are valued at about $192 million, coal at $27 million and steel at $117 million, according to a House Africa subcommittee.

Unlike the House-approved bill, the proposal also calls for $25 million in U.S. aid for education assistance to black South African refugees and for community development programs selected in consultation with black leaders but without the involvement of the South African government.

Provision for such aid was included in the compromise legislation worked out between the House and Senate last year but not enacted after Reagan announced his sanctions.

The prospects for Congress passing such new sanctions legislation before adjourning for the fall campaigns remain uncertain, according to House and Senate sources.

Rep. Howard E. Wolpe (D-Mich.), chairman of the House Africa subcommittee, said he plans to mark up the bill the first week of June and to bring it to a floor vote by the end of that month. The Senate, however, is unlikely to move as fast, sources said.