Four men are to appear in court charged with terrorism offences, the Crown Prosecution Service (CPS) said.
Zahid Iqbal, Mohammed Sharfaraz Ahmed, Umar Arshad and Syed Farhan Hussain will appear at Westminster Magistrates' Court in central London jointly charged with an offence contrary to section 5 (1) of the Terrorism Act 2006.
They are also individually charged with offences contrary to section 58 of the Terrorism Act 2000, the CPS said.
The charges come after five men were arrested last week in Luton on suspicion of the commission, preparation or instigation of acts of terrorism.
The CPS said it had concluded that there was insufficient evidence to prosecute the fifth suspect, and he has been released without charge.
Piers Arnold, specialist prosecutor from the CPS special crime and counter-terrorism division, said: "After carefully considering evidence gathered by the Metropolitan Police Service, I have concluded that there is sufficient evidence and that it is in the public interest to jointly charge Zahid Iqbal, Mohammed Sharfaraz Ahmed, Umar Arshad and Syed Farhan Hussain with an offence contrary to section 5 (1) of the Terrorism Act 2006.
"It is alleged that between January 1, 2011 and April 25, 2012 the men committed acts of terrorism, or assisted others to commit such acts, or were engaged in conduct in preparation for giving effect to that intention."
Mr Arnold said the alleged conduct included facilitating, planning and encouraging travel overseas; organising, encouraging and participating in physical training; purchasing survival equipment; downloading, researching and discussing electronic files containing practical instruction for a terrorist attack; discussing methods, materials and targets for a terrorist attack including firearms and improvised explosive devices; and collecting and supplying funds for terrorist purposes overseas.
He added: "All four men are also individually charged with offences contrary to section 58 of the Terrorism Act 2000, namely possessing documents likely to be useful for a terrorist purpose."