Offenders convicted of training as terrorists will face life sentences under tough new plans being drawn up.
Ministers are also understood to be looking at ending automatic early release and introducing a "two strikes and you're out" policy for serious terror offenders.
Current sentencing restrictions that allow a maximum 14 year sentence for terror training offences would be increased to life for anyone jailed for weapons training linked to terrorism as well as making or possession of explosives.
Convicts would serve their full prison term unless a panel of experts deemed them fit for release under the proposals being examined. The worst terror offenders would automatically be given a life term for a second very serious offence.
A Whitehall source told The Daily Telegraph: " People want to know that those who commit, or try to commit, terrorist offences face the toughest punishments.
"By increasing the maximum sentence to life, offenders like these won't get out of prison until the Parole Board judges them to no longer be a risk.
"Even when they're out, we'll still be keeping an eye on them and they can go straight back to prison if they break their life licence."
A Ministry of Justice spokesman said: "Those who endanger lives and threaten our national security deserve to receive long sentences.
"We are looking at options to further ensure that those convicted of the most serious terror offences are given the toughest sentences possible, plans will follow in due course."