New York police insist they were right to release details of the bombs that killed 52 people in London, even though they had not been vetted by UK police.
The bombs killed 56 people in London on 7 July
Deputy NYPD commissioner Paul Browne said commissioner Raymond Kelly was right to include details of the devices in a briefing for security experts.
These included saying the 7 July bombs had been detonated by mobile phones.
But Mr Browne said he regretted making an erroneous statement saying the details had been cleared by the Met.
He said he had made the statement believing it to be true but it had turned out to be wrong.
However, he maintained all the information released by the NYPD was unclassified and open source material.
He added that it was normal for New York police to release such information, saying: "We do this routinely with information we have about the elements used in terrorist attacks around the world.
"We've been doing it for three-and-a-half years - long before the incidents in London - and it's helped us educate the public."
Mr Kelly gave details of the bombs during a briefing for New York security industry bosses on information given to NYPD officers monitoring the investigation in London.
He said: "Initially it was thought that perhaps the materials were high-end military explosives that were smuggled - but it turns out not to be the case.
"It is more like these terrorists went to a hardware store or some beauty supply store."
The NYPD said investigators believed the bombs were made using a peroxide-based explosive that can be made from hair bleach and other ingredients.
Officials said the bombs had probably been made in Leeds and had been stored in a powerful refrigerator.
The substances used in the failed 21 July bomb attacks were "similar but not necessarily the same", a spokesman said.
The bombs were transported to the outskirts of London in drink coolers stashed in the boot of two cars and detonated by mobile phones that had alarms set to 0850 BST, the officials added.
Deputy commissioner of counter-terrorism Michael Sheehan said: "In the flophouse where this was built in Leeds, they had commercial grade refrigerators to keep the materials cool."
The NYPD was troubled by information it had received about the bombers' links to "organisations" he added.
"We know those same types of organisations that they are affiliated with are very much present in New York City.
"That is something we are studying very, very carefully.
"This could happen here."
Scotland Yard has refused to comment on the NYPD claims.