The Justice Department unsealed arrest warrants yesterday charging three Lebanese Shiites with the hijacking of a TWA airliner to Beirut last June, and the Reagan administration posted a $250,000 reward for information that would help convict the fugitives.

In disclosing the identities of the TWA hijackers for the first time, the department said it had charged Ali Atweh, Mohammad Hamade and Hasan Izzaldin with air piracy and murder in the 17-day seizure of TWA Flight 847 and the shooting death of Navy diver Robert Dean Stethem of Waldorf, Md. All three are believed to be in Lebanon.

The two-paragraph complaints are the latest move in a stepped-up campaign by administration officials to demonstrate strong action against international terrorism. U.S. officials disclosed earlier this week that they had issued arrest warrants for the four Palestinian hijackers of the Italian cruise ship Achille Lauro and Mohammed Abbas, the Palestine Liberation Front leader who is said to be mastermind of the plot.

Federal prosecutors began presenting evidence yesterday in the Achille Lauro case to the same grand jury that is investigating the TWA hijacking, but officials concede that chances of a U.S. trial in either case are slim. The four Palestinian ship hijackers are being prosecuted in Italy and Abbas' whereabouts are unknown. In the TWA case, U.S. officials have made no request for Lebanon to extradite the Shiite hijackers under a world antihijacking agreement, but Justice Department officials did not rule out seeking extradition.

Attorney General Edwin Meese III said yesterday's actions were part of "a determined, coordinated effort by the United States" to crack down on terrorism.

Justice Department officials initially resisted disclosure of the arrest warrants, which were filed in U.S. District Court here July 3, days after the TWA hostages were released. But prosecutors acceded to a State Department request to invoke a 1984 law authorizing the secretary of state to offer rewards up to $500,000 for information leading to a terrorist's conviction.

State Department spokesman Joseph Reap cautioned that "the reward money will be paid out only when we are satisfied that the information provided has led to . . . a final conviction and appropriately severe punishment."

The State Department also offered a $250,000 reward yesterday for information on a Kuwaiti Airlines hijacking last December in which two Agency for International Development employes were killed.

The three Shiite Moslems were charged under an amended version of the 1958 Federal Aviation Act, which gives U.S. authorities the power to prosecute hijacking or murder aboard an American plane anywhere in the world. Since the Achille Lauro was an Italian ship on the high seas, U.S. officials were unable to charge the ship hijackers with the murder of Leon Klinghoffer, 69, of New York, and were limited to hijacking-related charges.

TWA Flight 847 was hijacked June 14 with 153 passengers and crew on a flight from Athens to Rome. All but 39 of the passengers and crew were released in Algiers and Beirut as terrorists took the plane on an 8,500-mile odyssey.

The hijacking was carried out by militant Lebanese Shiites, members of the extremist Hezbollah, or Party of God movement, who demanded the release of 700 Shiite prisoners captured by Israel in its incursion into Lebanon. Israel eventually released the prisoners in stages.

Several former TWA hostages applauded the government's announcement. Kurt Carlson of Rockford, Ill., said the reward could be effective because "money speaks very strongly in that part of the world." Carlson, who was beaten by the hijackers, said he expects to testify if the hijackers are ever tried, adding, "I've got their faces ingrained in my mind."

In a related development, congressional and other officials yesterday confirmed a report in the Boston Globe that U.S. intelligence required nearly 24 hours to locate the Achille Lauro last week after the ship was hijacked. No reason was provided for the difficulty in finding the ship, which was eventually located by an Israeli vessel.