ISLAMABAD, Pakistan — Pakistani authorities denied entry on Thursday to an official of the Committee to Protect Journalists and forced him to leave the country, the journalist watchdog group said in a statement.

Steven Butler, the Asia program director of the Committee to Protect Journalists, was traveling to Pakistan to attend a human rights conference when he was stopped upon entry in the eastern city of Lahore. While Mr. Butler had a valid Pakistani visa, immigration officials told him that the interior ministry had put him on a “stop list” before confiscating his passport. Mr. Butler was forced onto a flight to Doha, Qatar, where he was then placed on another plane to Washington, D.C., C.P.J. said in a statement.

“Pakistani authorities’ move to block Steven Butler from entering the country is baffling and is a slap in the face to those concerned about press freedom in the country,” said Joel Simon, C.P.J.’s executive director. “Pakistani authorities should give a full explanation of their decision to bar Butler from entering and correct this error. If the government is interested in demonstrating its commitment to a free press, it should conduct a swift and transparent investigation into this case.”

There was no official comment from the Pakistani government on Friday.

Pakistan is considered a dangerous place for journalists. Intimidation, harassment and assaults are routinely reported, and several leading journalists have been attacked for their critical reporting on the country’s powerful military. In 2013, on the eve of general elections, the authorities ordered the expulsion of Declan Walsh, the Islamabad bureau chief of The New York Times, and gave no explanation.