NEW YORK (AP) _ CIA Director William Casey, who underwent surgery last month for removal of a brain tumor, is unable to speak, walk or control the right side of his body, according to ABC News.

The network, quoting unidentified sources, reported Monday that Casey is clear-minded and conscious, but said his condition makes it unlikely that he ever will retun to his job.

CIA spokeswoman Kathy Pherson, reached by The Associated Press on Monday night, would not comment on the report. White House spokesman Larry Speakes said today of the report, ''I don't have that information.''

Asked whether White House officials believed that Casey would be unable to return to work, Speakes said, ''That remains to be seen. We'll let the doctors make the decision.''

Meanwhile, presidential chief of staff Donald T. Regan, responding to reporters' questions as he arrived to visit the president at Bethesda Naval Hospital, said there were ''no plans to'' replace Casey.

Tracy Primrose, spokesman at Georgetown University hospital, said Casey remained in stable condition, but she would not provide additional information or comment on the report.

Casey underwent surgery Dec. 18 for the removal of the malignant tumor.

The White House was informed at least two weeks ago that it was unlikely Casey would return to work, and since then a search for a possible successor has been under way, ABC said.

Deputy Director Robert Gates has been running the CIA in Casey's absence, but is not considered a leading candidate to replace him, ABC said.

Several reports have said that those being considered for the job include U.N. Ambassador Vernon Walters and former senators John Tower and Howard Baker.

One administration official, speaking on condition he not be identified, told the AP it has been apparent from the outset that Casey probably could not resume his duties, but top White House officials, including White House chief of staff Donald T. Regan, have been reluctant to begin a search for a successor.

He said there is no sense of urgency, partly in deference to Casey's family, long-time friends of President and Nancy Reagan, and partly in the belief that Gates is well-equipped to handle the job of acting director.

The source insisted that no search for a replacement has begun within the White House and talk of possible candidates is speculation. However, Sen. Malcolm Wallop, R-Wyo, said Monday he has received ''feelers'' from the White House about succeeding Casey.

In a copyright story published today, Wallop told the Casper Star-Tribune that White House officials, whom he would not identify, expressed ''their interest in having me take over if they were going to replace Casey.''

''I haven't been asked, and I'm not running around pursuing it,'' he said.

He said doesn't expect to be offered the position because it likely would cost the Republican Party a Senate seat. If Wallop resigned, it would be up to Gov. Mike Sullivan, a Democrat, to appoint a replacement.