Sen. Edward Zorinsky (D-Neb.) said today that Nicaragua's deposed dictator, Anastasio Somoza, whose whereabouts have been unknown since he was asked to leave the Bahamas last weekend, is now in Guatemala.

The senator, here on a fact-finding mission, did not say where his information came from and offered no details of what Somoza might be doing in the nearby Central American country. But diplomatic sources here said they too have "indications" that Somoza is in Guatemala, probably meeting with right-wing groups there that supported his government until it was overthrown three weeks ago by the Sandinista National Liberation Front.

Leaders of the new government here have expressed concern that Somoza might try to organize a counter-revolution. There seems to be little reason to believe, however, that Somoza would find much support here for such an effort.

Zorinsky's comments came during a press conference this morning a few hours before he returned to Washington at the end of a three-day visit, the first by a member of Congress since Somoza's overthrow.

The senator, who met with members of the ruling junta, the Sandinista national directorate and the Cabinet, said he will recommend that the United States increase its emergency food and medical aid and approve loan guarantees for private American investment here.

He also said he believes the United States should quickly arrange an economic development package for Nicaragaua and "very seriously consider" providing arms to the country's new revolutionary government.

Zorinsky described the Sandinista and civilian government leaders with whom he met as a "dedicated, impressive group of people whose driving force is Nicaraguan nationalism. I think the best thing we can do is steer clear of trying to put a particular ideological stamp or imprint on this government."

In June, Zorinsky became the first member of Congress to call for Somoza's ouster. He recommended at that early date that the United States recognize the Sandinista front as Nicaragua's legitimate government.

Zorinsky, who is chairman of the Senate Foreign Relations Committee's Western Hemisphere affairs subcommittee, could do now is fail to help the new government when it desperately needs foreign aid to feed its people and rebuild the shattered economy.

If the United States falls to help the new government, Zorinsky said, "then we will help fulfill a prophecy by pushing them toward a Marxist government. I think this will happen only if the United States abdicates its responsibility in Latin America" and in Nicaragua in particular.

The senator said he was not offended by, or overly concerned about, continued references in the government-controlled press here to "U.S. imperialism" and statements by junta and Sandinista leaders criticizing aid efforts so far.

"I am aware of some posturing that is taking place," Zorinsky said "I'm a politician enough to know the way the game is played." He added that the government leaders with whom he talked did not once criticize U.S. relief efforts oor policies since the new government assumbed power July 19.

U.S. officials who attended Zorinsky's embassy press conference said the Carter administration is trying to increase its food and medical aid from an initial 43 tons a day to 150 tons in the near future.

"All we ask is that the Nicaraguan people are told that the American people are their friends and are extending a helping hand," Zorinsky said.

The senator also said that Interior Minister Tomas Borge had told him that the new government will begin releasing 100 prisoners a day in the near future. Some 10,000 persons, mostly members of Somoza's National Guard, are being held.

Zorinsky said he will brief President Carter and members of Congress on his trip.