Radical Muslim cleric Abu Hamza has lodged an appeal over his extradition from the UK to America with Europe's human rights judges, the Home Office said.
Hamza's extradition is on hold while a panel of judges decides whether the Grand Chamber of the European Court of Human Rights (ECHR) should hear his appeal, which was made on the eve of the 10 July deadline.
Hamza, 54, was jailed for seven years for soliciting to murder and inciting racial hatred and will remain in extradition custody.
It is expected to be between six and eight weeks before the panel decides whether to hear the appeal.
The move is also expected to delay four cases related to the same judgment, including that of Babar Ahmad, a 36-year-old computer expert and alleged terrorism fundraiser who has been held in a UK prison without trial for nearly eight years.
The other cases involve Seyla Talha Ahsan, Adel Abdul Bary and Khaled Al-Fawwaz.
The European Court of Human Rights in Strasbourg said on 10 April that "detention conditions and length of sentences of five alleged terrorists would not amount to ill-treatment if they were extradited to the USA".
Confirming Hamza's appeal, the Home Office said it welcomed the original judgment but noted it will not become final until any appeal is decided.
All five men will remain in extradition custody, a spokesman added.
The unanimous ruling from the judges in April said there would be no violation of Article 3 of the Human Rights Code - the prohibition of inhuman and degrading treatment - as a result of detention conditions the five men might face at ADX Florence "supermax" prison in the US.
The length of their possible sentences would not breach their human rights under European law either, the court found.
The judges said that between 1999 and 2006 the men were indicted on various terrorism charges in America.
Hamza has been charged with 11 counts of criminal conduct related to the taking of 16 hostages in Yemen in 1998, advocating violent jihad in Afghanistan in 2001 and conspiring to establish a jihad training camp in Bly, Oregon, between June 2000 and December 2001.