Justice Secretary Chris Grayling has set out the terms for the pre-legislative inquiry into whether prisoners should be granted to right to vote.
He said: "Parliament is sovereign in this area.
"Nobody can impose a solution on parliament but the accepted practice is that the United Kingdom observes its international obligations."
Shadow justice secretary Sadiq Khan said allowing prisoners serving less than four years to vote would lead to 30,000 inmates going to the polling stations.
More top news
Donald Trump has wasted no time making his mark on international matters as well as domestic. So how will his presidency affect the world?
Another cold, frosty and foggy night for many. Northern and western areas will see thickening cloud, patchy rain and milder temperatures.
Temperatures have already plunged to -12C in some parts of the UK this winter - but Thursday could be the coldest day yet.