LONDON — British anti-terrorist police charged three more people late Tuesday with conspiring to commit murder in the alleged plot to blow up U.S.-bound airliners.

The three -- Mohammed Yasar Gulzar, Mohammed Shamin Uddin and Nabeel Hussain -- were also charged with preparing to commit terrorism by helping in an alleged plan to smuggle explosives aboard the planes, police said.

Eleven people have now been charged on those two counts. Four others were charged with lesser offenses, including having knowledge of a terrorist activity but not disclosing information about it.

A Scotland Yard statement said Gulzar, Uddin and Hussain conspired with eight other suspects in the alleged plot and had intended to commit "acts of terrorism engaged in conduct to give effect to their intention to smuggle the component parts of improvised explosive devices onto aircraft and assemble and detonate them on board."

All three men will be arraigned on Wednesday.

Of 25 people originally arrested, 15 have been charged and are being held by police, five others remain in custody without charge and five have been released.

Chief Magistrate Timothy Workman earlier ordered Nabeel Hussain's brother Mehran Hussain held in custody until Sept. 19. Mehran Hussain, and his other brother, Umair, are charged with failing to tell police about Nabeel's alleged involvement in what prosecutors say was a plot to down airliners using plastic and liquid explosives.

Workman also ordered Cossar Ali, 24, held in custody until Sept. 5, when her lawyer David Gottlieb said he intends to apply for bail. Ali, the only woman charged so far in connection with the alleged plot, is accused of failing to disclose information about a possible terrorist attack.

Her husband, Ahmed Abdullah Ali, also is among the 15 people charged in the case.

Earlier in the day, a 17-year-old accused of storing an explosives manual and other documents connected to an alleged plot to blow up trans-Atlantic airliners was denied bail during a court appearance.

The teenager, who cannot be identified, was remanded until a Sept. 19 hearing at City of Westminster Magistrates' Court.

His attorney, Gareth Peirce, said the teenager intended to plead not guilty. He faces up to 10 years in jail if convicted, prosecutor Colin Gibbs told the court.

Gibbs told the court the teenager is accused of storing an explosives manual, a map of Afghanistan and five wills made out by people planning to commit suicide bombings -- items police consider likely connected to planned acts of terrorism.

A deadline for the detention of the remaining five suspects held without charge expires on Wednesday, but a police spokesman said it was not yet decided whether they would be charged or if police would seek further time for questioning.

Senior police officers said last week they were analyzing thousands of pieces of evidence seized in searches of dozens of properties and two stretches of woodland.

Investigators have found chemicals that can be used to make bombs, including hydrogen peroxide, and electrical components during their searches, said Peter Clarke, head of Scotland Yard's anti-terrorist department.

Months of surveillance had produced "significant video and audio recordings" about the alleged plot, he said, including "martyrdom videos" by some of the suspects.

More than 8,000 items of data storage, such as compact discs, DVDs and memory sticks, were found, authorities said.