Knesset members have been visiting Hamas prisoners in Israeli jails - to make the point that they can.

They are furious that wings housing Hamas prisoners are open for visitors, while Gilad Shalit is held by Hamas in an undisclosed location, with his family desperate for news of his wellbeing and even the Red Cross are barred from visiting.

Politicians who made the rounds of cells at Ofer Prison near Jerusalem last week - Shaul Mofaz of Kadima, Miri Regev of Likud and Eitan Cabel of Labour - want to give Hamas a taste of its own medicine. They want to worsen conditions for Hamas prisoners, while meeting the minimums required by international law, until Sergeant Shalit's are improved.

They say that Israel's security prisoners have a cushy time during incarceration. As well as receiving family visits they may send a letter a week and receive unlimited mail, have access to cable television, and get budgets to spend in prison tuck shops. They also have the right to enrol on degree programmes, and at any one time an estimated 250 prisoners are studying. Last year, a security prisoner earned a PhD.

The idea of tying Hamas prisoners' conditions to Sgt Shalit's is not a new one.The Knesset endorsed the idea last year, passing a bill at its first reading.

But many such bills start because politicians like the general gist of them, but subsequently fall. As the second reading is expected soon, backers of the bill are desperate to raise its profile -hence the prison visit.

While before the first reading, Prime Minister Benjamin Netanyahu threw the weight of the coalition behind the bill, several key people in his office are now known to be raising misgivings about it.

If the bill is returned to the Knesset without coalition support, it is unlikely to pass. But why the hesitation? At first glance, this bill would seem a political no-brainer. It would prove popular, with Mr Shalit's plight moving the public and the treatment of security prisoners angering it.

But the government sees negotiations over Sgt Shalit as exceedingly delicate, and is well aware that Hamas will use any excuse to blame a further breakdown on Israel.

If the plan backfires and Hamas halts all talks on Sgt Shalit, blaming Israel's new policy, Israel would be seen internationally as taking a share of the blame, and domestically the negative reaction against the government would be strong - possibly strong enough to bring it down.