LONDON (BLOOMBERG) - Britain is rushing to pass a law to halt the automatic release of people jailed on terror-related offences who complete half their sentences - before the next convict becomes eligible at the end of the month.

The measure comes after 20-year-old Sudesh Amman was shot and killed by police after stabbing two people in south London on Sunday - just over a week after he was released from prison having served half a three-year sentence for possessing and disseminating terrorist information.

Amman was still considered a threat and was under intensive police surveillance, but authorities had no means to keep him in prison under current legislation.

In November, a man who had been automatically released halfway through a 16-year sentence stabbed two people in central London before he was shot by police.

Prime Minister Boris Johnson's government is now racing to change the law before Feb 28, when someone else convicted of terrorist offences is due for automatic release, according to a government official who asked not to be named.

Five more people are due for release in March.

Under the proposed legislation, convicted terrorists will serve at least two thirds of their sentences and will have no right to automatic release, Justice Secretary Robert Buckland told the House of Commons this week.

Instead, the parole board will carry out a risk assessment, he said.

The Bill will be introduced in the House of Commons on Feb 11, with the goal of getting it passed by both houses of Parliament by Feb 27.

But the schedule could be tight, with just three days planned to get the Bill through the upper House of Lords.

Human rights campaigners may also object to the measure.