The 29-year-old celebrity was stopped by immigration authorities upon her arrival in Japan on Tuesday, one day after her plea, according to an e-mailed statement by Hilton's representative, Dawn Miller. Hilton spent the night at an airport hotel after being questioned by officials. She was scheduled to appear at a news conference in Tokyo on Wednesday to promote her fashion and fragrance lines, but that appearance was canceled.

"We interviewed her yesterday and we may interview her again today. We are continuing the immigration process to determine whether she can enter Japan or not," said Kazuo Kashihara, an immigration official at Narita. He declined to give a reason for the delay, but under Japanese law, immigration authorities are empowered to deny entry to those who have been convicted of drug-related offenses.

Officials at the US Embassy in Tokyo declined to comment. The front desk at her hotel said calls to her room could not be connected.