NAIROBI, Kenya - Uganda's top opposition leader has been kicked off a flight from Kenya, prompting a small protest back home that police quickly quelled with tear gas one day before the country's president of 25 years was due to be sworn in for another term.

A leader in Kizza Besigye's political party said Wednesday that the opposition politician would not return to Uganda until Friday, one day after President Yoweri Museveni is sworn in for his latest term.

Kenya Airways said Besigye was not allowed to board because the airline had learned the plane would not be cleared to land in Uganda if he were on it.

But in Uganda, Minister of Information Kabakumba Matsiko told parliament that the government did not block Besigye's return, but that former Kenyan President Daniel arap Moi was on the plane and did not want Besigye on it. The former president was travelling to Uganda for Thursday's inauguration.

Moi's spokesman, Lee Njiru, said the former president has no say in who rides on a Kenya Airways flight. "He has nothing to do with it. This is an irresponsible utterance," Njiru said.

Anti-government marches led by Besigye over the last month have been the most serious unrest in sub-Saharan Africa since protests swept out leaders in Egypt and Tunisia. Human Rights Watch says that Uganda security forces have killed nine people during the protests.

Museveni, who first came to power in 1986, has said repeatedly that his government will not fall to protests. He was re-elected in February and his inauguration is set for Thursday.

Several hours after being barred from the plane, Besigye told journalists that he was scheduled to take a Kenya Airways flight to Uganda Wednesday evening. But later, a top leader in his political party, Anne Mugisha, said Besigye would not return until Friday.

Besigye said the country's constitution guarantees him the right to return home.

"Every Ugandan has the right all the time to return to Uganda. So it's a contradiction that he wants to swear by that constitution tomorrow which he is violating today," Besigye said. "This is what we are confronting -- impunity."

Kenya Airways said in a statement that Besigye was denied boarding because "internal intelligence sources" said the aircraft would not be allowed to land in Uganda if he were on board. The airline said Besigye was not allowed to board so that other passengers were not inconvenienced.

Besigye, who election officials said finished second in the vote, has been arrested five times while leading protests over rising prices and government corruption. During his last arrest, he was sprayed at point-blank range with tear gas or pepper spray. He was temporarily blinded and sought medical care in Kenya.

An official at Kenya's Jomo Kenyatta International Airport said airport officials received instruction from Kenya's government to block Besigye from travelling by air. The official spoke on condition of anonymity because he is not authorized to speak publicly.

A Kenyan member of parliament, meanwhile, accused Kenya's government of colluding with Museveni to frustrate Besigye. Charles Kilonzo said Kenya was working with Museveni to fight the opposition in Uganda.

Government spokesman Alfred Mutua denied the government's involvement, saying that "there is nothing like that." In a statement, Mutua said Besigye had missed his flight and that he has been booked on a later flight.

"Besigye is free to travel within Kenya or travel from Kenya at any time or day of his choice," Mutua said. "He is free to take any flight of his choice. The government of Kenya is not involved in his travel plans."

Food and fuel prices have risen sharply in Uganda in the past few months, fueling the anti-government protests. Museveni said he will propose a constitutional amendment so that protesters are jailed for at least six months after arrest, instead of being released on bail the same day.