A Spanish judge has ordered that three Algerians be jailed on charges of having links to al-Qaeda.
Garzon is investigating suspected al-Qaeda cells in Spain
A Spaniard accused of collaborating with the three men was also jailed, pending further investigation.
Judge Baltasar Garzon said the Algerians had helped other militants,
some of whom had links to those involved in the 11 September attacks.
The four were arrested in raids across Spain on Friday - they are said to be members of Iraq-based Ansar al-Islam.
Spanish news agency Efe said the judge had also asked the UK to hand over Ansar al-Islam member Heidi Ben Youssef Boudhiba or "Fathi", who he described as the Algerians' leader.
The three Algerians have been named as Mohamed Ayat, Samir Mahdjoub, alias Sami Menardo, and Redouane Zenimi, alias Bachir. The Spaniard is identified as Francisco Garcia Gomez.
The Algerians are accused of recruiting people and sending them to terrorism training camps in Iraq.
Mr Mahdjoub and Mr Zenimi were also accused of forging passports to help recruits travel to Iraq.
The charges against the men fall short of a formal indictment, but they allow
the suspects to be held for up to two years as investigations continue.
After the men's arrests last week, a Spanish interior ministry official said they were not believed to be linked to the 11 March attacks in Madrid which killed 191 people.
Judge Garzon is investigating suspected al-Qaeda cells operating in Spain.
In 2003 he called for the arrest of 35 men, including Osama Bin Laden, for their alleged involvement in the 11 September attacks on the US.