Police in Pakistan have re-arrested Asif Ali Zardari, the husband of former Prime Minister Benazir Bhutto.
Police clash with Zardari supporters at the airport
Mr Zardari was detained at Islamabad airport on the orders of a court after he failed to attend a hearing in a murder trial in the city of Karachi.
There were clashes between police and hundreds of Zardari supporters who had gathered at the airport to greet him.
He was freed on bail last month after eight years in jail on charges ranging from corruption to murder.
Observers say the release, with the cases still pending, may have been part of moves by the government to end its long stand-off with Pakistan's secular opposition.
Mr Zardari has now been flown back to Karachi where he has been placed under house arrest.
BBC correspondents say the authorities may have been unnerved by the reception Mr Zardari has received from opposition supporters in the weeks since his release and may want to keep him away from the capital.
Judge Pir Ali Shah of the special anti-terrorism court in Karachi cancelled Mr Zardari's bail on Tuesday when he failed to show up in court.
Mr Zardari faces charges of conspiracy to commit murder in the 1996 killing of a judge and his son. He denies the charges.
He had travelled from Karachi to the Pakistani capital to address a political rally.
Police arrested him the moment he stepped off his plane.
Mr Zardari said they had no right to prevent him from attending a public meeting.
"We are going to challenge this - I have been in prison and I know these tactics," Mr Zardari told the BBC's Urdu service by mobile phone while his lawyers checked the arrest warrant.
"I condemn this undemocratic step. It's against my basic right of movement."
Mr Zardari was released from jail last month
Earlier, he told the AFP news agency that the cancellation of his bail showed the government "are scared of my popularity".
The government, however, says the law is taking its course because Mr Zardari failed to turn up in person in court.
"Naturally, the bail has been cancelled and this is the orders of the court, and we will go by the court orders," Interior Minister Aftab Ahmed Khan Sherpao said on Pakistan television.
Hundreds of Zardari supporters had gathered at Islamabad airport ahead of his arrival.
When they heard he had been arrested they tried to storm the VIP lounge, smashing windows.
Police fired tear gas and baton charged the protesters to disperse them. A number of protesters were detained.
Benazir Bhutto has lived abroad since 1999
"This is sheer barbarity," one opposition MP, Aitzaz Ahsan, told the Associated Press at the scene.
The Pakistan People's Party (PPP), which Ms Bhutto heads, said a number of party supporters had also been detained in Rawalpindi on Monday night.
"It's an insult to democracy. It's the worst example of
dictatorship," PPP parliamentary leader Makhdoom Amin Fahim told a news conference.
The events add up to another extraordinary twist in Mr Zardari's story.
But the BBC's Paul Anderson in Islamabad says his re-arrest may not mean the government is going back on efforts to smooth relations with the PPP.
Our correspondent says Mr Zardari may have challenged the legal system and found it can fight back.
Benazir Bhutto, who also faces corruption charges in Pakistan, was twice prime minister.
Her governments were dissolved in 1990 and 1996 for alleged corruption. She went into self-imposed exile in 1999.