John Reinhardt, director of the U.S. Information Agency, pledged yesterday to let the Voice of America broadcast "straight news" about the United States -- warts and all.

In an interview, Reinhardt, a black and a career Foreign Service Officer, also said:

The USIA is building four new transmitters to step up its signal in eastern and southern Africa as part of the new U.S. initiatives for black rule on the continent.

China continues to be the only nation jamming Voice of America broadcasts.

The USIA is immersed in reorganization involving all aspects of "public diplomacy." For example, the cultural and educational office in the State Department may be transferred to USIA.

President Carter's human rights statements are being broadcast by VOA.

Reinhardt was asked if the VOA will present the news straight, even if it reflects poorly on America.

"Absolutely," he said. "It's in our interest. The radio that isn't credible is a useless radio. If a foreigner tunes into the Voice of America for news, he ought to be able to get it and be sure what be's heard is straight news."

Reinhardt said he is "well acquainted" with allegations that the VOA sometimes tailors its news, and he cited the VOA decision not to broadcast news about the 1975 U.S. evacuation from Vietnam. Similar criticism was made of the VOA Watergate coverage.

"Most of the allegations I think are without foundation," Reinhardt said.

He said he issued guidelines several weeks ago to ensure that VOA provides "straight news -- untampered, unfiltered in any way,- and he plans to increase the number of stories about ordinary American life.