A last minute amendment to the Police Bill proposed by the Labour front bench would establish specialist units with the Crown Prosecution Service and the Metropolitan Police to speed up decisions about the arrest of war criminals.

The amendment has been tabled by Shadow Police and Criminal Justice Minister Vernon Coaker.

The new units would report directly to the Director of Public Prosecutions, who would have to sign off all warrants under the new legislation.

Under the present system , magistrates are able to issue arrest warrants for alleged war criminals. Over the past two years, several prominent Israeli politicians and military figures have cancelled visits to Britain for fear of being arrested. Israeli Opposition leader Tzipi Livni was briefly issued with a warrant in December 2009 after an application from lawyers acting on behalf of pro-Palestinian campaigers.

Conservative Party leader David Cameron said he would change the legislation on universal jurisdiction if his party came to power and the coalition has held to the pledge.

Supporters of the Labour amendment argue that the new units would reassure people that the new system would not slow down the arrest of any genuine war crimes suspects.

The proposed amendment is also designed to pacify backbenchers uncomfortable that the legislation could water down the principle of universal jurisdiction for crimes against humanity.

However, some Labour supporters of Israel believe the amendment is dangerous compromise to Labour's Left.

Meanwhile, the veteran Labour campaigner Anne Clwyd has proposed a wrecking amendment, to remove altogether the clause passing responsibility for war crimes arrest warrants to the DPP. This has so far been signed by 30 MPs.