By Laura Smith-Spark and Nicky Robertson
LONDON (CNN) -- British police arrested two men following a trespassing and burglary incident at Buckingham Palace this week, authorities said Saturday.
The Metropolitan Police are still investigating the incident Monday night in which at least one man scaled a security fence to gain entry to the palace.
One man was arrested for burglary, trespass and criminal damage, police said.
The man was found inside the palace in an area open to the public during the day, police said. The second man was arrested for alleged conspiracy to commit burglary.
No members of the royal family were at the London residence during the incident, police said.
The incident has prompted a review of security at Buckingham Palace, the best known of Queen Elizabeth II's palaces.
It's not the first time an intruder has managed to get into the central London palace.
In 1982, Michael Fagan was arrested in the queen's bedroom after gaining access to the building via a drainpipe. According to news reports from the time, the queen woke to find him by her bed and talked with him until she was able to raise the alarm.
That incident led to promises of tighter security at the palace. Other incidents have occurred since, but none has involved anyone getting as close to the queen as Fagan did.
However, in 2004, a fathers' rights campaigner dressed as Batman evaded security to stage a protest on a Buckingham Palace balcony.
Jason Hatch, a Fathers 4 Justice campaigner, used a ladder to scale the perimeter fence before climbing onto the balcony, where the royals appear on ceremonial occasions such as the wedding of Prince William and Catherine in 2011.
Concerns escalated after a Daily Mirror reporter got a job at Buckingham Palace as a servant before U.S. President George W. Bush stayed there during a state visit in November 2003.
Stand-up comedian Aaron Barschak had highlighted lax security by gate-crashing Prince William's 21st birthday party at Windsor less than six months earlier.
Buckingham Palace's 19 State Rooms, filled with magnificent paintings, sculpture and antique furniture, are open to paying visitors in summer, when the royal family is elsewhere.
The palace is the administrative center for the royal household, as well as the queen's London residence.
Laura Smith-Spark reported from London and Nicky Robertson reported from Atlanta.
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