BAGHDAD, Iraq — A pair of bombs rocked a busy shopping district in the Iraqi capital yesterday, killing at least 55 civilians and security officials and injuring 131 in a devastating attack on a neighborhood that had begun to emerge from the doldrums of war.

One of the blasts was caused by a suicide bomber wearing an explosives-packed belt, an official at the Iraqi Ministry of Interior said.

The explosions erupted just before 7 p.m. as shoppers and pedestrians walked along the streets of the busy and well-lit Karada district, on a Thursday night, which is the equivalent of Friday night in the West.

The attack appeared to have been designed to inflict maximum casualties. The first explosion went off in a dumpster near an outdoor produce market, killing three and injuring a dozen.

The disruption attracted onlookers, rescuers, and security officials. The suicide bomber was among the crowd. He set his belt off about five minutes after the first explosion, security officials said.

“I ran outside to see what was going on, only to have the second blast going off,” the 27-year-old proprietor of a shop selling new and used clothing 200 yards away from the site of the explosions, Kareem Abdullah, said. “I could see fire and smoke. I saw people thrown to the ground. I couldn’t tell if they were unconscious or dead.”

At least 16 of the dead and 28 of the injured were security officials on hand to help the victims of the first explosion. The blasts crushed shops and mangled more than a dozen motor vehicles.

[Meanwhile, the Associated Press reported that America insisted yesterday that a meeting between Iran and Washington about Iraq’s security was never scheduled, a day after Iran announced that the meeting would take place.

A spokesman for the American Embassy in Baghdad, Philip Reeker, said that the talks, which would have been the fourth in a series of rare meetings between Tehran and Washington, were never planned.

“If some party thought there was a meeting scheduled, there was a misunderstanding,” he told reporters in a conference call. “We were not expecting any meeting because no meeting was scheduled.”

On Wednesday, Iran’s state news agency, IRNA, reported that an Iranian delegation had arrived in Baghdad for the talks, which it said would take place yesterday. An Iraqi government official said the Americans declined late Wednesday to meet with the Iranian delegation, and the Iranians would return to Tehran after visiting Shiite Muslim shrines in Baghdad and in the holy city of Karbala. The official spoke on condition of anonymity because he was not authorized to speak to the press.

The Associated Press also reported that Iraq and China are close to re-signing a $1.2 billion oil deal that was called off after the 2003 American invasion, an Iraqi Oil Ministry official said yesterday. Saddam Hussein’s government signed a deal with the state-owned China National Petroleum Corp. to develop the billion-barrel al-Ahdab oil field, despite U.N. sanctions that barred direct dealings with Iraq’s oil industry. Beijing was waiting for the sanctions to end when the American invasion overthrew Saddam. The two countries restarted talks in October 2006.]