MPs were turned away from the House of Commons chamber as water poured in through the ceiling because of a leak.
The sitting was delayed for 60 minutes as numerous buckets near the green benches were catching drips raining in through the ceiling on Monday afternoon.
Staff were trying to keep the chamber dry, with protective coverings draped over the central table.
With the weather over Westminster exceedingly warm and dry, the cause of the leak was unclear.
But there have been repeated delays to plans to restore the crumbling Palace of Westminster, amid concerns of soaring costs.
A House of Commons spokesman said: “Due to a water leak in the House of Commons chamber, the start of business was delayed. Maintenance staff took action to resolve the situation, and the House is expected to sit from 3.30pm.”
Business in the chamber was scheduled to start at 2.30pm with prayers followed by work and pensions questions.
Some MPs were arriving at the chamber unaware of the situation.
Two police officers were also seen entering the Commons chamber with packages labelled as water-absorbent blankets.
Labour MP Emma Hardy, who briefly walked into the Commons chamber before being turned away, told the PA news agency the water leak appears to be “just in front of the despatch box”.
The MP for Kingston upon Hull West and Hessle said: “I have just walked through and there are a lot of people working, around six or seven.
“Lots of blankets on the floor and a machine, which I’m not quite sure what is doing.
“It (the leak) is just in front of the despatch box, but the roof looks fine.”
Somebody has just said to me this is one leak where we don’t need an inquiryDeputy Speaker Nigel Evans
Ms Hardy said she has been told the issue should be resolved “as quickly as possible”.
Deputy Speaker Nigel Evans added: “Somebody has just said to me this is one leak where we don’t need an inquiry.”
Conservative MP Flick Drummond (Meon Valley): “We have got DWP questions, which are really important. So it is a bit irritating to have that starting late. And it pushes everything else back too, so we might have a very late night tonight.”
Asked if the incident made her concerned, she replied: “Yes, I have done the basement tour. This is a very dangerous place to be.
“I can tell you, we need to do some restoration very quickly on this and perhaps I think the only way we are going to do that is to move out now because it’s going to be too expensive.
“But yes, we have water leaks, we have things falling down from ceilings and downstairs, the electricity cables and gas and water leaks.”
In April 2019, water pouring into the Commons forced an abandonment of the sitting.
This occurred during a debate on tax matters and while proceedings carried on for a few minutes, the noise of water pouring into the press gallery soon became overwhelming.