Police have been given an extra seven days to interview nine men arrested in Birmingham over an alleged plot to kidnap and kill a Muslim soldier.
Searches are being carried out at 12 addresses
They needed the extension to continue holding the suspects beyond the initial 48-hour period allowed under anti-terror legislation.
Three chose to attend the hearing at Coventry Magistrates' Court, while the others were represented by lawyers.
Meanwhile, police scientists have been combing 12 premises across Birmingham.
The men were arrested under the Terrorism Act on Wednesday over what security sources say was a plan to film the soldier being executed and post it on the web.
This means police have a maximum of 28 days to hold them.
The BBC's home affairs correspondent Andy Tighe said the applications were heard by City of Westminster district judge Nicholas Evans, who deals with many alleged terrorism cases in London.
Earlier, police said the investigation was likely to continue for "days, if not weeks".
Forensic scientists have been continuing searches of raided properties as police officers handed out 5,000 leaflets to local people, in an effort to reassure them.
They include details on what to do if anyone comes under attack as a consequence of the raids and have been translated into Punjabi, Hindi, Bengali and Urdu.
On Thursday morning, Home Secretary John Reid updated the Cabinet on the ongoing situation , Downing Street sources told BBC News.
BBC defence correspondent Paul Wood said the Ministry of Defence was worried such alleged plots could hinder efforts to recruit more Muslims.
There are currently 248 Muslims in the armed forces - out of a total of 100,000 personnel.
Police are trying to reassure locals by keeping them informed
Zeeshan Hashmi - whose brother L/Cpl Jabron Hashmi became the first British Muslim soldier to be killed in Afghanistan last July - said rumours he was the target of the alleged plot were untrue.
Mr Hashmi, from Bordesley Green in Birmingham, also served in Afghanistan but is now studying in Cambridge.
He told BBC News: "Initially people thought it was I, but, no, to make it very, very clear, I wasn't at the centre of the plot."
Wednesday's arrests - orchestrated by police and the security service MI5 - followed many months of activity.
Shortly after 0400 GMT, officers swooped on 12 addresses in the Sparkhill, Alum Rock, Kingstanding and Edgbaston areas and made eight arrests.
Among the properties raided were two houses and a general food store in Alum Rock and the Maktabah book store in Stratford Road, Sparkhill.
Less than 12 hours later, police announced in a press conference they had arrested a ninth person on a motorway in the Birmingham area.
Dame Pauline Neville-Jones, former chairman of the Joint Intelligence Committee, said kidnappings in the UK would be "much nearer a form of psychological warfare that we've seen obviously elsewhere".
Human rights lawyer Amer Anwar said intelligence reports surrounding such arrests should not be taken as fact.
"We should remember the Forest Gate incident where what we talked about was suicide bombs and belts that were supposed to have been found in the place and, in the end, it all turned out to be absolutely 100% wrong."
Last June's anti-terror raid in Forest Gate, north London, in which a man was shot in the shoulder, did not lead to any charges.
But BBC correspondent Gordon Corera said security sources and police were confident about the intelligence that led to Wednesday's raids.
Many local people said they had been shocked by Wednesday's arrests and the scale of the operation.
Police have also set up an information line on 0121 626 6663.
1. Two properties raided in Jackson Road, Alum Rock
2. House raided in nearby Foxton Road
3. End of terrace house searched in Poplar Road, Sparkhill
4. Bookshop raided in Stratford Road
Further raids at Ward End Park Road (5) and Asquith Road (6)
Police also searched properties on Showell Green Lane (7) and Golden Hillock Road (8) near Sparkhill
Police are reported to have also raided properties in the Edgbaston (9) and Kingstanding (10) areas of the city