LONDON (AFP) -The alleged ringleader of the July 7 London bombers was recorded in an intelligence operation last year, the BBC reported.

Mohammed Sidique Khan, 30, was secretly filmed and recorded speaking to a British-based terror suspect, a source told the British Broadcasting Corporation.

The investigation suggested that he was in contact with activists from Al-Qaeda, Osama bin Laden”s global terror network, for five years before the London blasts which killed 52 commuters and the four bombers themselves.

Khan &#34had extensive contacts with an international jihadi network which British intelligence either missed or ignored&#34, the BBC said.

He featured in a surveillance operation by intelligence services, according to the joint radio and television investigation.

The BBC”s source said he had seen photographs and transcripts of a meeting between Khan and the suspect, who could not be named for legal reasons.

When the suspect was detained last year, the source said Khan contacted him demanding an urgent meeting, wanting to know what the security services found out about the suspect.

The BBC said that on both occasions when the source met Khan, he had three other men with him, who were not the three named by police as the other London bombing suspects — raising the possibility that three other Khan associates &#34are still on the loose&#34.

The BBC said there was no independent corroboration that Khan was recorded talking to the terror suspect.

However, the report said that if correct, it would amount to &#34a serious failure of intelligence&#34 leading up to the July bombings.

The information &#34would show the intelligence services had him well in their sights but allowed him to slip away&#34.

Terror suspect Nasir Abbas, held in Indonesia over the 2002 Bali bombings, alleged that Khan travelled to Malaysia and the Philippines in 2001 to meet leaders of the extremist Islamist group Jemaah Islamiyah, closely linked to Al-Qaeda, the report said.

The BBC interviewed Singapore-based academic researcher Dr Rohan Gunaratna, who spoke to Abbas after the July attacks.

&#34He was received by Hambali who is the operation leader of Jemaah Islamiyah,&#34 Gunaratna told the BBC.

Alongside Abbas, he visited a training camp in the Philippines run by Al-Qaeda trainers, Gunaratna said.

The report also alleged that when Khan visited Pakistan in 2003 he met an Islamic extremist and Al-Qaeda fixer currently in US custody.

The Metropolitan Police have declined to comment on the BBC report.

The police force identified Khan, a British Muslim of Pakistani origin, as one of the four men who blew up three Underground trains and a double-decker bus.

The teaching assistant was linked to the bomb in an Underground train near Edgware Road station, which killed seven, himself included.

Khan hailed from Dewsbury in northern England.

In September, a message from the grave left by Khan aired in an Al-Qaeda video that claimed credit for the July 7 suicide bombings.

In footage on the Arabic television station Al-Jazeera, a man identified as Khan told viewers that Western atrocities against Muslims drove him to bomb the London Underground.

A 27-year-old man arrested in Dewsbury on Saturday is the only person in police custody in connection with the July 7 bombings.