KARACHI, Pakistan  — A judge in Pakistan is asking police to file formal charges against an FBI agent arrested there after allegedly carrying ammunition and three knives onto an airplane.

FBI agent Joel Cox is free on 1 million rupees — about $9,800 — bail. Police investigator Khalid Mahmood says Cox appeared Saturday before a judge in Karachi, the capital of southern Sindh province.

Mahmood says police told the judge they need more time to file formal charges. Cox is expected back in court May 19.

Cox arrived in Karachi on May 1 and was detained Monday after officials found him with the ammunition, knives and electronic devices as he was preparing to board a flight to Islamabad.

The arrest is a new strain on relations between Pakistan and the U.S.