Pakistani authorities said Wednesday that an FBI agent whom they jailed on weapons charges is not likely to be released until at least the weekend.

Joel Cox, 32, an agent from the FBI Miami Field Office, was arrested Monday while trying to board a commercial airliner traveling from Karachi to Islamabad, the capital. Pakistani police said he was attempting to carry ammunition onto the flight.

Officials said Cox is being held in his own cell, away from other prisoners, and was allowed to meet Wednesday with a U.S. Consulate representative and two lawyers. But U.S. officials appear to be having little success in getting him released quickly.

An official with the Pakistani Foreign Ministry said Cox will probably remain detained until a judge rules on his case. A hearing is scheduled for Saturday.

The judicial process will take its due course,” said an official in the Foreign Ministry, who spoke on the condition of anonymity to discuss the matter freely.

U.S. officials have said that Cox was part of a multi-agency effort to help the Pakistanis investigate corruption. They said he had forgotten that the ammunition was in his carry-on bag and voiced optimism that the matter can be resolved.

But Pakistani security officials released information Wednesday that they say raises more questions about Cox’s work in Pakistan.

Rao Anwar, a senior police official in Karachi, told journalists that the agent landed in Pakistan on May 1 with a standard traveler’s visa good for three months.

When he was arrested, he was carrying 15 bullets and a magazine for a 9mm pistol, as well as three knives and several small cameras, Anwar said.

“He was a foreigner, not a diplomat,” the police official said, referring to the kind of visa Cox carried. The fact that he had that visa might make it difficult for him to claim diplomatic immunity.

A former FBI agent who used to work in Pakistan said agents are permitted to carry weapons there but are not allowed to take them onto civilian aircraft.

A spokesman for Prime Minister Nawaz Sharif declined to comment. Muhammad Ali Saif, a prominent Islamabad-based defense lawyer, expressed doubt that political leaders could short-
circuit the judicial process even if they wanted to. He noted that Pakistan has a strong, independent judiciary.

“Now that [Cox] has been handed over to the police for an investigation, under the law, this period has to expire and he couldn’t be set free before that,” Saif said.

At the State Department, spokeswoman Jen Psaki said that “we are hopeful” the matter will soon be resolved. She said the FBI agent had been in Pakistan on temporary duty, working with the legal attache at the U.S. Embassy.

The incident seemed unlikely to seriously strain bilateral relations, which have been improving .

In Pakistan, even conservative Islamic political parties have been largely silent on the matter. And although Cox’s arrest was national news there, the country is consumed with the ramifications of a World Health Organization decision to label the country a major source of the polio virus.

Aftab Khan Sherpao, a Pakistani lawmaker and former interior minister, said he considers Cox’s detention far less serious than the 2011 arrest of another American, Raymond A. Davis, on murder charges.

Davis, who was a CIA contractor based in Lahore, fatally shot two men who he said had been trying to rob him. He was detained for two months and freed after the U.S. government agreed to compensate the victims’ relatives.

“This was recovery of a few bullets, not any weapon,” Sherpao said .

Craig reported from Kabul. Karen DeYoung in Washington, Shaiq Hussain in Islamabad and Nisar Mehdi in Karachi contributed to this report.