The families of the three men and other supporters had earlier held a small protest outside the city of Westminster magistrates court where el-Banna had appeared.
"The moment we finally get them to Britain ... and to within touching distance, almost, of their children, [and] suddenly the Spanish come up with this"
Clive Stafford-Smith, lawyer for the three men
Deghayes was later released without charge, but then re-arrested on a similar Spanish extradition warrant, AFP news agency reported.
His sister, Amani Deghayes, told Al Jazeera earlier on Thursday that her brother's arrest had stunned and angered the family.
"It's just absolutely sick - first we're told he's just going to have a formal interview then be released ... and then a bombshell last night at 11 o'clock that he may be extradited to Spain and ... [we] may not see any kind of trial for two years," she said.
"It's really outrageous and sick [and] we weren't prepared for that."
Meanwhile Clive Stafford-Smith, lawyer for the three men, told Al Jazeera that he had been assured by the Spanish authorities while Deghayes was in Guantanamo Bay that they would not seek his extradition.
"The moment we finally get them to Britain... and to within touching distance, almost, of their children, suddenly the Spanish come up with this," he said.
"The idea thay they would suddenly try to swoop in on him is just immoral."
El-Banna, a Palestinian-Jordanian who has the right to live in Britain, was originally detained in November 2002 while on a business trip to Gambia with another man, Bisher al-Rawi.
The pair were thought to have been taken to Afghanistan by US authorities and then to Cuba.
El-Banna is accused by Spanish authorities of being a member of an al-Qaeda cell, known as the Islamic Alliance, in Madrid between June 1996 and July 2001.
His release on bail means he will be reunited with his family, including his youngest child whom he has never seen.
Deghayes, meanwhile, was arrested in Pakistan, while Samuer was picked up on the Afghan-Pakistan border.
The British government changed its policy of refusing to seek the release of non-British nationals in August.
The US has been criticised internationally for its detention policies at the prison camp.
It has said in the past that it does not want the facility to remain open for a protracted period of time.
Washington did not say why it had decided to comply with Britain's request to release the men from the base in Cuba.
Britain's interior ministry had said on Wednesday that the three men's return to Britain did not mean they would be permitted to stay in the country.