Uganda on Thursday denied it had agreed to receive thousands of African migrants as part a deal with Israel.
The denial came a day after Israel launched the program to force some 38,000 migrants, mainly Eritreans and Sudanese, to leave the country.
Israel has not clearly said where the migrants will go, but tacitly recognizes it is too dangerous to return the Sudanese and Eritreans home.
As a result, according to activists in Israel, it has signed deals with Rwanda and Uganda, which agree to accept departing migrants on condition they consent to the arrangement.
Uganda, however, said it had made no such deal.
"Uganda is disturbed by these reports," foreign affairs minister Henry Okello Oryem told AFP. "We have no such agreement with the government of Israel to send refugees here."
African migrants pour out of the Holot Detention Centre in Israel's Negev desert after their release on August 25, 2015 Menahem Kahana (AFP)
There was no immediate reaction from Rwanda.
Under Israel's program, migrants have until the end of March to leave. Each will receive a plane ticket and $3,500 (2,900 euros) to do so, and those who remain will face arrest.
Holot, an open facility in Israel's desert south that can host 1,200 migrants who are allowed to leave to work during the day, is also set to be closed.
In Israel on Wednesday, Adi Drori-Avraham, from an NGO called ASSAF (Aid Organisation for Refugees and Asylum Seekers), told AFP: "From what we know, Uganda is a party to the amended agreement, allowing that people can be coerced into leaving."
"It has published a denial, although I have to say that Uganda has for years been denying that it has some kind of deal with Israel," he said.
"But we see that thousands arrive there so I don't know how much Uganda's denials should be taken seriously."
When the plan was first announced in November, the United Nations refugee agency expressed concerns.
Netanyahu has since defended the plan, speaking about it at his party cabinet meeting on Wednesday he said, "every country must maintain its borders, and protecting the borders from illegal infiltration is both a right and a basic duty of a sovereign state."
Holot Negev afp
Referring to the migrants as "infiltrators", the prime minister warned that they can "either cooperate with us and leave voluntarily...or we will have to make use of the other means at our disposal."
Migrants started coming in large numbers across the porous border between Israel and Egypt's Sinai Peninsula in 2007, when nearly 5,000 entered, interior ministry figures show.
The government has since completed fencing the border and deploying electronic sensors. In the first six months of last year, no one made it across.
Over the years, those caught at the Egyptian frontier were detained at prisons in the Negev desert in southern Israel.
On release they were given bus tickets to Tel Aviv, arriving at the central bus station on the south side of the city.
Israeli residents of southern Tel Aviv have long complained of their presence and right-wing politicians have pledged to heed calls to force them out, often with harsh rhetoric.
