The news agency says the men were carrying political banners when they were detained at the staff entrance of the palace on Wednesday morning.
Asked about the case Thursday, police would only confirm that two men aged 26 and 20 years old had been charged with trespassing on a sensitive site.
The palace had no immediate comment.
Buckingham Palace is one of about 30 royal, government and military sites protected by special legislation.
Central London has seen several demonstrations in the past two months by students angry at tuition hikes imposed by the government. One protest saw.
Meanwhile, the palace is preparing to play host to hundreds of invited guests for the April 29 wedding of Prince William and Kate Middleton.
It was revealed last week that Queen Elizabeth II, William's grandmother, will host a reception there after the wedding ceremony.
The reception guest list has not been released, but palace officials said it will be drawn from members of the wedding congregation who make up both the couple's official and private lives.
That evening, Prince Charles is to host a dinner and dance at Buckingham for family members and close friends of the newlyweds. They'll also spend the night under the palace roof before heading off for a still-undisclosed honeymoon.