Home Secretary David Blunkett is making a statement on royal security in the House of Commons on Tuesday.
Mr Barschak said he was surprised by security
He warned on Monday that those involved in counter-terrorism and personal protection had their "heads on the block" after Aaron Barschak managed to gatecrash Prince William's 21st birthday celebrations at Windsor Castle, Berkshire.
The security lapse has left police "devastated", said Scotland Yard Commissioner Sir John Stevens.
The country's most senior policeman said on Tuesday that lessons would be learned to ensure it never happens again.
It's my job to make
sure that what happened at the weekend never happens again
In a newspaper interview, Mr Barschak - a stand-up comedian who had dressed as Osama Bin Laden for the stunt - has told of how he kissed the prince on both cheeks.
According to the Daily Mail interview, the comedian wandered around the castle's grounds for almost an hour.
The police officer he spoke to helpfully gave him directions to the celebrations after accepting Mr Barschak was a drunken guest who had become lost.
"The security was non-existent", he told the paper.
"I was carrying a bag which could have had a bomb in it.
"I was just yards away from the Queen and Prince Charles.
"If I had been a real terrorist the entire Royal Family would have been wiped out."
Inside the party, the comedian delivered his comedy routine and then kissed Prince William on both cheeks before heading towards the bar.
Only then was he challenged and eventually arrested.
He has now been released on police bail and will have to wait to find out whether he will face charges.
Sir John Stevens has personally apologised to Royal Family for the blunder.
"Let's make it absolutely clear, the royal protection department, which makes
up part of the Metropolitan Police Service, is devastated by what took place at
Windsor Castle over the weekend," he said.
"We have got to pick up the pieces of what's going on. It's my job to make
sure that what happened at the weekend never happens again."
Mr Barschak said the crowd listening to William at the event laughed at the comedian's appearance and applauded him out of the room once he had finished.
Barschak climbed over a wall and talked his way into the party
The paper said the comedian had been preparing to return to north London when he saw his opportunity to gain access to the castle, noticing an embankment on the north side of the building.
Mr Barschak climbed the embankment and then went up a tree next to the perimeter wall, before dropping over it.
He was spotted wandering around by a contractor, who assumed he was a guest and took him through a gate to a nearby police officer.
The comedian told the paper: "The whole time I was inside the castle, I was expecting to trip an alarm, to be picked up on CCTV, or to be confronted by a policeman."