Repatriation flights were halted a day after the two governments announced the start of an operation to return more than 600 Senegalese migrants from the Canaries, where nearly 9,000 sub-Saharan Africans have come ashore in boats this year.
Senegal's surprise move was a setback to a diplomatic effort by Madrid to gain the cooperation of West African governments to halt an exodus of thousands of illegal migrants trying to reach Europe via the Canary islands.
Hundreds are believed to have drowned in perilous ocean voyages of more than 1,000km undertaken in open boats from the coasts of Mauritania and Senegal.
"Senegal is suspending its cooperation with Spain in the operations to repatriate its citizens from the Canary Islands," the senior official, who asked not to be named, told Reuters.
A first batch of nearly 100 Senegalese illegal migrants were flown to Dakar from the Canaries on Wednesday.
The official complained that the migrants were handcuffed and told before they boarded they were going to Spain, although the plane flew them to Dakar.
"We'd hoped that the repatriation would be carried out in a dignified manner. That wasn't the case," the official said.
Senegal wants migrants to
be treated with dignity
Spain's foreign and interior ministries declined to comment.
Diplomats in Dakar confirmed the repatriation flights had been suspended.
"If you tell these people (the migrants in the Canaries) that they are going to be flown back home, then they won't get on the plane," one diplomat said, asking not to be named.
Senegal sent a diplomatic note to Madrid protesting the treatment of its nationals and suspending the repatriation operation, he added.
The migration wave has become one of Spain's hottest political issues and the conservative opposition says criminals are sneaking into Spain through leaky borders.