JERUSALEM — About a dozen Palestinian businessmen defied the official Palestinian boycott of the Trump administration’s economic conference in Bahrain last week.

Once there, most of them tried to maintain a low profile and keep their names out of the news media. The delegation returned to the West Bank on Thursday. But officers of the Palestinian Authority’s General Intelligence Service arrested one of them, Saleh Abu Mayala, on Friday night as he was walking from his car to his home in the West Bank city of Hebron, according to two Palestinian officials and the leader of the Palestinian business delegation to Bahrain, Ashraf Jabari.

One Palestinian official called his attendance at the conference an illegal act of betrayal.

Mr. Abu Mayala was later released, Jason D. Greenblatt, the White House’s special Mideast envoy, said in a post on Twitter. Palestinian officials had maintained official secrecy about the arrest, and it was not clear when exactly he was freed, but he was released without charge.

Prime Minister Benjamin Netanyahu said on Sunday at the start of his weekly cabinet meeting that Mr. Abu Mayala had been released “due to American pressure.”