NEW YORK, May 5 (Xinhuanet) -- Police are questioning a UN employee from the Netherlands who was near the site of Thursday morning's explosion of two makeshift grenades outside the British Consulate in Midtown Manhattan, law enforcement sources said.

    The man tried to get into a secure police zone following the blast, but sources would not say whether he is a suspect.

    The blast occurred shortly before 4 a.m. inside a concrete planter on the sidewalk. The explosion tore off a chunk of the planter and shattered part of the building's glass facade. The shrapnel spread nearly half a block, but no people were within range, police said.

    The explosion happened as national elections were held in Britain, with Prime Minister Tony Blair facing public anger about the Iraq war in his re-election bid. However, officials stressed that it was not clear whether the consulate itself had been target. the building also houses a variety of domestic and foreign companies.

    "We do not at this point have any idea who did it or a motive," mayor Michael Bloomberg said at a press conference Thursday morning. "But we have the best people investigating, and I think eventually we'll find out who did it, and we'll apprehend them."

    No threats of such an attack had been made, Bloomberg said, and no one has claimed responsibility.

    Police pieced together the shrapnel and determined the devices were novelty grenades that had been filled with gunpowder. They were apparently buried in the soil of the planter and lit with a fuse by hand. There was no evidence of a timing device, authorities said.

    Police searched the area for more explosive devices, but nothing was found. Security videos in the area are being reviewed, and the Federal Bureau of Investigations counter terrorism task force is assisting the investigation, said Police Commissioner Ray Kelly.

    The consulate occupies the ninth and 10th floors of the 14-story glass and steel building, which has a bank and retail shops on the ground floor. Bloomberg said he expected the building, including the consulate, to be open for business later in the day.

    The streets around the consulate reopened by 10 a.m., but there could be more periodic closures as police investigate throughout the day.

    Confusion reigned, as many people came out of subway stations in the area without any idea what had happened. Police would only allow people in if they had identification proving they worked at companies on the block. Enditem