* Plane returns to South Africa after mid-air divert
* Ravalomanana allies quit government in protest
* Ousted leader still hopes to return (Recasts throughout)
By Ed Stoddard and Alain Iloniaina
JOHANNESBURG/ANTANANARIVO, Jan 21 (Reuters) - Madagascar's exiled former leader Marc Ravalomanana was back where he started on Saturday after a plane flying him home was ordered to turn around mid-flight and returned to Johannesburg's main international airport.
Ravalomanana's second failed bid in less than a year to return could have ended in his arrest and would have stoked political tensions on the impoverished Indian Ocean island. He has been in self-imposed exile for almost 3 years since his toppling in a military coup
Madagascar's government rejected accusations it had denied the plane permission to land.
However, instructions from the government for a number of the island's airports to be shut down, including Antananrivo, during the afternoon are detailed on the website of the Agency for Aerial Navigation Safety in Africa and Madagascar, an African traffic control agency.
The former leader's political allies said they were pulling out of the country's consensus government in protest.
"In light of this act of provocation, we have decided to suspend our involvement in the government. We will not take part in cabinet meetings," said Mamy Rakotoarivelo, head of Ravalomanana's movement and president of the national parliament.
In Johannesburg, a spokesman travelling with Ravalomanana said the ousted leader still hoped to return.
"There will be further negotiations and he has every confidence that (South African) President Jacob Zuma will use his influence to help resolve this matter," spokesman Peter Sullivan told Reuters by telephone.
Thousands of his supporters, many of whom wore t-shirts adorned with his portrait, had streamed towards the airport in Madagascar's capital and military police had formed a cordon at the airport's entrance, blocking their access to the terminal.
The supporters broke out into song after news of his turn around seeped out into the crowd.
"We're hugely disappointed. What's happening underlines the lack of political goodwill from Rajoelina. What's the point in being a part of this transition," supporter Michel Damamy told Reuters as rain began to fall and the crowd slowly dispersed.
Ravalomanana was sentenced in absentia to life in prison for the killings of demonstrators by elite troops in the run-up to his removal.
The dairy tycoon's return was the subject of heated debate and was a major stumbling block in negotiations over a political road map that ushered in a new interim government.
The current leader, Andry Rajoelina, warned Ravalomanana's presence in the world's fourth largest island risked raising tensions. A senior cabinet minister said in September that Ravalomanana would be arrested on arrival.
ACTIVE ARREST WARRANT
If he and when he does return he could still face arrest. The country's chief prosecutor said an old arrest warrant remained active.
Among Madagascar's wealthiest individuals, Ravalomanana built up his fortune in a classic rags to riches tale.
Selling yoghurt on Antananarivo's streets in his early twenties, he soon secured a World Bank loan with the help of a Protestant church to set up his own factory.
His critics accused Ravalomanana, who was mayor of Antananarivo before holding the top office, of abusing his political power to build up his empire.
Famed for its leaping lemurs and mist-filled rain forests, Madagascar's tourism industry has suffered badly from the political turmoil. Foreign investors who have been eying its oil, gold and chrome have also been wary of committing to the impoverished nation. (Additional reporting by Shafiek Tassiem; Writing by Ed Stoddard and Richard Lough; Editing by Sophie Hares)