* Rare attack in central Islamabad, 11 dead
* Taliban declared month-long ceasefire over the weekend
* Judge, policeman among those killed, 30 wounded (Adds details, quotes)
By Maria Golovnina
ISLAMABAD, March 3 (Reuters) - Gunmen burst into a court in a busy shopping area in the centre of the Pakistani capital on Monday, killing at least 11 people in a brazen attack likely to shatter any prospect of meaningful peace negotiations with Taliban insurgents.
A loud explosion reverberated across central Islamabad just after 9 a.m., followed by bursts of gunfire. Police said at least 30 were wounded. A judge was among those killed.
"There was a blast, then there was a lot of gunfire. Gunmen were spraying bullets at everyone," said Faisal Ali, a businessman who witnessed the attack.
No one immediately claimed responsibility, but the attack is likely to show that the central Taliban leadership, which declared a month-long ceasefire over the weekend, is not fully in control of its operations.
Taliban fighters stage frequent attacks around the country, but such assaults are rare in Islamabad, the leafy and hilly seat of Pakistan's government.
Broken glass and charred human remains littered the site of the blast at the F8 market area as residents and police rushed around in bloodstained clothes. A severed leg lay atop the rubbble.
Pools of blood and severed body parts were scattered on the floor of several offices. Police said gunmen fired at random targets in the area after the initial court explosion.
Police blocked entry and exit points to the area, a maze of narrow, dusty streets lined with one-room shops and offices.
Camouflaged commandos knocked on doors and secured street corners as they combed through the area for more militants.
"There is one policeman among the dead," local police station head constable Mohammad Yousaf told Reuters.
"We also have unconfirmed reports that two lawyers have died. There is a lot of chaos on the scene right now and things will become clearer soon."
The Taliban, a fragmented group consisting of dozens of smaller bands of militants, said this weekend they would observe a one-month ceasefire to try to revive peace talks and called on all groups to observe it.
Talks broke down last month after a series of attacks and counterattacks by the army and the insurgents. (Additional reporting by Mehreen Zahra-Malik; Editing by Ron Popeski)