Fugitive ex-CIA agent Edwin P. Wilson, arraigned yesterday in U.S. District Court here, will challenge the legality of his arrest earlier this week by federal officials, his lawyer said.

Judge John H. Pratt turned down a request by Wilson's lawyer, John Keats, to postpone the arraignment for one week. Keats said he wanted the delay to "verify information regarding Wilson's detention in the Dominican Republic and his arrest" in New York on Tuesday.

Wilson fled to Libya after his indictment here in April 1980, on charges of providing Libyan dictator Muammar Qaddafi with explosives, terrorist equipment and training.

Justice Department officials said that Wilson was captured after he was tricked into leaving Libya for the Dominican Republic, where, according to department officials, he was convinced he would have a "safe haven."

Wilson, traveling on a false Irish passport, left Libya Monday on a commercial flight to Zurich, where he was followed by deputy U.S. marshals. The deputies were on the same flight that Wilson took to Madrid and from there to the Dominican Republic, where Dominican officials refused to allow him to enter the country and put him on to a flight to New York.

Pratt gave Keats until July 14 to file preliminary motions challenging the arrest. In the meantime, he ordered Wilson to remain in custody under a $20 million bond. The U.S. Attorney's office declined to say where Wilson is being held.

Speaking to reporters afterward the hearing, Keats would not say why he thought the arrest procedures were illegal. Justice Department officials have said that Wilson left Libya after he was assured by an associate that he would not be arrested, but they would not comment further on how Wilson was persuaded.

Wilson, 53, appeared weary and subdued during the 10-minute proceeding yesterday, but Keats said afterward that Wilson was "in good spirits" and predicted a "long and difficult trial" in the next few months.

Francis E. Terpil, another former CIA agent indicted along with Wilson, is still a fugitive and is believed by federal officials and former associates to be living in Beirut.