Commons Speaker Michael Martin has said he takes "very seriously indeed" suggestions that security services could tap MPs' phones.
Mr Martin said he could not discuss security issues in the Commons
During prime minister's questions, Tony Blair said he would discuss extending MI5 powers following recent recommendations by intelligence chiefs.
It would mean the end of a 40-year-old ban on the practice introduced by the then prime minister, Harold Wilson.
Labour MP David Winnick told Mr Blair MPs should have a vote on any changes.
Critics of the move, including former Defence Minister Peter Kilfoyle, say scrapping the ban on tapping would undermine MPs' freedom.
At prime minister's questions, Mr Winnick asked Mr Blair to pledge that there would be a debate and a vote before any change to the policy was made.
Mr Blair said the issue had nothing to do with him wanting to tap MPs' phone "in the wake of terrorism, of Iraq or anything else".
Instead, the Interception of Communications Commissioner Sir Swinton Thomas had recommended the change.
"Those are recommendations I am obliged to reflect upon," he said. "I will reflect upon them and discuss it obviously with colleagues and we will come forward with proposals when we are ready."
Immediately after prime minister's questions Scottish National Party leader Alex Salmond, asked the speaker for a ruling on the issue.
Mr Martin replied: "He raises an important matter and I will reflect on what he has had to say and what the prime minister has had to say.
"And I also say it puts a responsibility on my shoulders because I cannot discuss security matters on the floor of the House but the honourable gentleman will understand I do take this matter very seriously indeed."
Mr Salmond told reporters outside the Commons the proposal as "ridiculous".
He added: "George Galloway may be in the Big Brother house, but this is a case of Big Brother Blair, and MPs on all sides of the House will not have it."
Defence Secretary John Reid has said the Cabinet is being advised to drop the ban and the idea is "worthy of deep reflection and more consideration".
Covert surveillance of MPs has been banned since 1966 years under a convention known as the Wilson Doctrine, named after Prime Minister Harold Wilson, who established the rule.
He gave MPs a pledge that their phones would not be tapped and subsequent prime ministers have regularly confirmed it remains in place.
New powers to monitor e-mail and other communications were brought in 2000 as part of the Regulation of Investigatory Powers Act.