A US lawmaker has introduced legislation to end "inhumane and unconstitutional" rules that prevent death row inmates from presenting newly discovered evidence to dispute their guilt.

- We’ve got folks on death row with no opportunity to show compelling new evidence of innocence - Democratic Representative Hank Johnson of Georgia said upon unveiling his proposal this week.

Johnson's measure, hailed by human rights group Amnesty International, would allow federal courts to give death row prisoners more opportunities to present newly discovered evidence that demonstrates probable innocence.

It would also let inmates file more habeas corpus appeals challenging their detention if and only if they offer new evidence that a panel of federal judges rules may be reasonably expected to demonstrate innocence.

If a federal court were to grant a habeas corpus petition, the case would likely return to the court where it was first tried for a retrial, supporters of the legislation say.

Underlining that current restrictions on appeals may lead to innocent people being executed, Johnson warned      -The status quo is inhumane and unconstitutional.-

About 139 people have been wrongfully convicted and send to death row over the last three decades in the United States, according to Amnesty International, which advocates abolishing capital punishment altogether.

Legal in 35 of the 50 US states and used regularly in about 12 of them, the death penalty has been reconsidered recently in 11 states, largely because of the high costs associated with its use.