Egyptian media outlets reported that several members of Egypt’s military and security services appeared to be among those arrested. Egyptian authorities seemed eager to play down the plane’s seizure: Two journalists covering the episode were detained in Cairo without charge on Saturday, then released on Sunday.

They were the latest of at least 200 journalists to be arrested under the decade-long rule of President Abdel Fattah el-Sisi, whose government and security services own or control most of the Egyptian press. Mr. el-Sisi’s government, which has attempted to polish the country’s human rights record recently with overtures toward its political opposition and releases of several high-profile political prisoners, has not commented on the events of the last week.

Zambia and Egypt have close ties, even though Zambia is often celebrated for its democratic governance and Egypt is often criticized as repressive. In June, Mr. el-Sisi visited Zambia to strengthen regional trade between northern and southern Africa.

The seized jet, a Bombardier Global Express that can seat up to 16 passengers, was carrying nearly $5.7 million in U.S. currency, 602 bars of the fake gold, five pistols and 126 rounds of ammunition. Zambian officials also seized a second, smaller passenger aircraft owned by a Zambian operator, which was believed to be linked to the first plane, Mr. Banda said.

In Zambia, the ballooning scandal has become a test of the country’s resolve to crack down on corruption and the impunity of the political elite. The authorities led news tours of the seized planes and offered public assurances that the cash would not go missing, in a show of the country’s push under President Hakainde Hichilema to root out corruption.