Radical preacher Anjem Choudary says his arrest was "politically motivated" after being released on bail on suspicion of being a member of a banned terrorist group.
He was one of 11 men held as part of a police investigation into alleged support of extremist group Al Muhajiroun.
The 47-year-old, who is to answer bail in January, tweeted: "I've been released from police custody.
"Just in time for Cameron to declare war on Islam & Muslims in Iraq & Syria."
Sheikh Omar Bakri Mohammad He was among nine men, aged between 22 and 51, held in London on suspicion of being members of a terror organisation and encouraging terrorism.
Two more were stopped and detained near junction 1 of the M6, just outside Rugby, Warwickshire.
One of the arrested men - 39-year-old Trevor Brookes - has been charged with two counts of breaching his notification requirement, while seven others have been bailed.
The pair held on M6 remained in custody.
A number of properties - 11 in east London, one in west London, one in northwest London, five in south London and one in Stoke-on-Trent - were searched as part of the investigation.
One of them was Yummy Yummy, a sweet shop in Whitechapel, East London, owned by Mr Choudary's brother Yadzani.
Mr Choudary said after his release: "My arrest certainly was politically motivated.
"The last time the government proscribed any organisation linked to me or previous groups I have been linked to was in June 2014.
"They have done nothing since then. They waited until the day before a major vote on a war against Muslims for a high-profile series of arrests."
Mr Choudary said he was questioned at Southwark police station about being a member of up to 10 banned groups including Islam4UK and Need4Khalifah.
He was reported to have said this week he had no sympathy for aid worker Alan Henning, who has been captured by the Islamic State in Syria.
He reportedly said: "In the Koran it is not allowed for you to feel sorry for non Muslims. I don't feel sorry for him."
Al Muhajiroun was set up by Mr Choudary and Sheikh Omar Bakri Mohammad, who was told he could not return to the UK after the 7/7 bombings.
The organisation was banned in the UK in 2010.
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