A police marksman who shot and wounded a suspect during an anti-terror raid on a London row house was cleared of any wrongdoing Thursday by Britain's police watchdog.

About 250 police joined the operation, acting on intelligence that a chemical bomb was being kept in the house in the Forest Gate neighborhood of east London.

During the pre-dawn raid June 2, an officer shot Mohammed Abdul Kahar, 23, point-blank in the shoulder. Kahar and his brother, 20-year-old Abul Koyair, were detained, but released without charge after a week of questioning. No bomb was found.

Britain's Independent Police Complaints Commission said in a report that the armed officer accidentally discharged his weapon after he confronted Kahar on a staircase, stumbled and fell against a wall.

"There is no evidence to support the speculative reporting that the weapon was fired by one of the brothers, or that it was a deliberate act by the police officer," commissioner Deborah Glass said.

"In the circumstances, I conclude that the officer has committed no criminal or disciplinary offense," she added in a statement.

The Metropolitan Police welcomed the report, particularly its finding that Kahar was immediately beside the officer who opened fire, not farther away as Kahar contended. The report kept the officer's identity secret.

"In this case, an independent forensic scientist has concluded that the weapon was within 2 inches of Abdul Kahar when discharged and was not in a normal firing position," Assistant Commissioner Tarique Ghaffur said.

Within minutes of the report's publication, police arrested Kahar on suspicion of possessing child pornography. He was freed Thursday night but was ordered to return for more police questioning at an undisclosed date.

Scotland Yard's Child Abuse Investigation Command said its detectives questioned Kahar on suspicion of involvement in collecting or making pornographic images involving children. The unit said the images were found on a computer seized in Kahar's home.

In a statement Kahar's law firm, Birnberg Pierce, said its client "strenuously denies" having anything to do with child porn. The firm accused police of arresting Kahar on the same day of the report to prevent him from reading and reacting publicly to it.

Kahar's sister, Humeya Kalam, said she was "deeply disgusted" by the report's exoneration of the police officer who fired the shot.

"They haven't done a thorough investigation. They seem to have rushed it," she said, contending that investigators initially told her family that the probe was likely to last seven months, not two.

Birnberg Pierce said it was "utterly mystified to learn that the (complaints commission) has not interviewed the officer who shot our client or any other officers present in the house." It said investigators instead "accepted statements that the officers prepared themselves, a most unusual and unsatisfactory practice."

But Glass rejected both criticisms.

"We have never stated that the investigation would take seven months. We made a public commitment to publish our findings as soon as possible, and that is what we have done," the commissioner said.

Glass said the probe did not need to interview the officer who opened fire.

"Our conclusions are based on forensic evidence, not on the account of the officer, or that of Mr. Abdul Kahar," she said.

The report said the firearms officer entered the property with the safety catch of his Heckler & Koch MP5 carbine switched off, an accepted practice in raids considered high risk.

CountryWatch: United Kingdom

While climbing a staircase, the officer said in his statement, he saw two figures rapidly approaching him.

"He and the two figures came into contact and this caused him to lose his balance and come into contact with the wall," the report said.

The officer said one or both people were pulling at his right arm and he feared for his life.

Kahar told investigators he had woken up to find several men dressed in black inside the house and believed the house was being robbed.

Community leaders last month held protests and accused police of being heavy-handed in their tactics and deliberately targeting Muslim families. Kahar at the time told reporters their only crime had been to be "Asian with a full-length beard."