Information Minister Hassan al-Lozy confirmed that Umar Faruk Abdulmutallab spent two extended periods in Yemen, as recently as this month, and that authorities were trying to determine what he did during that time.
Investigators said he spent at least part of the time studying Arabic at a school in the capital of San'a, where students and administrators described him as friendly and outgoing with no overtly extremist views. As part of the investigation, the principal of a school where he studied was being questioned Tuesday.
U.S. authorities have been trying to determine how Abdulmutallab, 23, managed to board a flight from Amsterdam to Detroit with explosives even though he was flagged on a watchlist as a possible terrorist. U.S. officials have said he told investigators after his arrest that he received training in Yemen.
Al-Lozy said that the U.S. never shared its suspicions about Abdulmutallab with Yemen, a largely lawless country that has turned into a key stronghold for al-Qaida.
"We didn't get any notice from the Americans to put this man on a list," al-Lozy said. "America should have told Yemen about this man, as they have of others."
Abdulmutallab lived in Yemen for two different periods of time, a year from 2004-2005 and from August-December this year, he said. He arrived in August after receiving a visa to study Arabic in the capital San'a.
Yemen's Foreign Ministry said Monday Abdulmutallab received a Yemeni visa after authorities were reassured that he had "several visas from a number of friendly countries." It noted that Abdulmutallab had a valid visa to the United States, which he had visited in the past. The embassy has now been instructed not to issue any more visas to students who want to study in the country without Interior Ministry approval.
The San'a Institute for the Arabic Language told The Associated Press that Abdulmutallab was an Arabic student at the school in August. That has raised questions about what he did the rest of his time in Yemen. Administrators at the school said Monday that the director of the school, Muhammad al-Anisi, has spent two days being questioned by Yemeni security officials. He remained in custody Tuesday.
Al-Lozy later told The Associated Press authorities are also looking into Abdulmutallab's frequent visits to a mosque in the old, historic part of the city and the people he was with during his stay in Yemen.
Students and administrators at the institute said Abdulmutallab was gregarious, had many Yemeni friends and was not overtly extremist. They noted, however, he was open about his sympathies toward the Palestinians and his anger over Israel's actions in Gaza.
The students and administrators spoke on condition of anonymity because Yemeni security authorities have ordered them not to talk to the media.
Al-Qaida in the Arabian Peninsula claimed responsibility for the attempted attack on the airliner and said it was retaliation for a U.S. operation against the group in Yemen.
More than 60 militants were killed in airstrikes last week believed to have been carried out with U.S. assistance.