Commons Speaker Michael Martin today rebuked a Tory MP for "rushing" to make a point of order about police entering his office.
Mr Martin told Daniel Kawczynski that he should have waited to get his "facts together" before making a statement to the Commons last night.
He said the police officer who requested a piece of constituency correspondence had acted with "good faith".
The officer entered the Shrewsbury and Atcham MP's office yesterday afternoon as part of an investigation into a series of letters containing white powder sent to the Commons.
Raising a point of order last night, the MP said he found the situation "disgraceful" following the controversial arrest of shadow immigration minister Damian Green and the search of his Commons office in November.
Mr Kawczynski said that to his "great embarrassment and eternal shame", he was "so weak" that he handed over the letter.
But in a statement today, Mr Martin said Mr Kawczynski's staff had previously arranged a time to meet the officer.
Mr Kawczynski later thanked the Speaker for his statement.
He said: "I was notified of them (police officers) being in my office while I was here in this chamber speaking in an opposition debate, and my members of staff felt - junior members of staff - felt under a certain duress to hand over documents.
"I'm extremely grateful to you that you have said in future, even if it does not involve parliamentary privilege, that the Serjeant at Arms should first be told if a police officer wishes to enter the office of an MP."
Mr Martin said the MP "must understand" that the approach made by the police officer to his staff was "done in good faith".
He said: "As I said, other honourable members have been put in a dangerous situation because of the particular investigation that's been going on.
"And I would only ask that honourable members, before they rush to point of orders and before they make statements that can reflect badly on professional people who are doing a decent job of work, that the best thing they can do is to sit and wait for a while and get the facts together."
He added: "That would have been the best thing and I think that the honourable gentleman's approach would have been perhaps different if he'd have given himself a breather and thought about what was going on."
In his statement earlier, Mr Martin said a police officer based in Westminster "sought assistance" from Mr Kawczynski's staff and agreed a time to meet them.
The MP agreed to hand over the document after being told details of the case, he said.
The Speaker added that any request for help from an MP or their staff should have been made through Commons Serjeant at Arms Jill Pay.
He said: "While I accept in this case the police officer acted with good intentions, I have instructed that any police officer assigned to duties in the House must advise the Serjeant at Arms of the intention to seek the assistance of a Member and his staff in his offices.
"The Serjeant at Arms will in turn approach the Member before the police take further action."
It is understood that one of the original letters which prompted the police investigation was sent to Children's Secretary Ed Balls. The white powder it contained was found to be flour.
A Metropolitan Police spokesman said the officer did not ask to search the office and no search was conducted.
He added: "A piece of correspondence matching handwriting of those under investigation was removed from the office after permission was granted by the MP."Reuse content