Trespassing in royal buildings could become a specific criminal offence under plans being considered by ministers after recent protests.
Jason Hatch's protest caused security fears
It comes after the Fathers 4 Justice protest on a Buckingham Palace ledge.
On Thursday, a Tory peer complained that if an international terrorist got into the Palace, he could only be charged with "non-criminal trespass".
Home Office Minister Lady Scotland said the government was giving "anxious attention" to the issue.
There were a number of laws which could be used to prosecute Palace invaders but no specific ones, she said
"That is the issue to which we are now giving the most careful consideration, because we do think there may be a strong argument for introducing a specific ... criminal offence, just in relation to the Queen's premises and perhaps certain other security sites."
She said she hoped there would be an announcement soon on the issue.
Last month fathers campaigner Jason Hatch scaled a wall at the Palace dressed as Batman.
Metropolitan Police chief Sir John Stevens said he would have been shot had officers thought he was a terrorist.
In May it was reported that Home Secretary David Blunkett was considering new laws to give royal premises the same protection as foreign embassies.
Legislation creating a "royal trespass" law was first recommended after comedian Aaron Barschak gate crashed Prince William's 21st birthday party dressed in an Osama bin Laden beard at Windsor.