Israel's decision to launch an air strike against a suspected nuclear site in Syria allegedly set up with the help of North Korea came after Israel shared intelligence with the US, it was reported today.

The attack on September 6 has been shrouded in mystery, although the Israeli opposition leader, Binyamin Netanyahu, yesterday confirmed in a TV interview that such an attack did take place. His admission came despite a news blackout over the incident.

The Washington Post today shed more light on the raid, which has sparked widespread speculation that it was a dry run for a possible attack on Iran's nuclear facilities.

The paper said the Bush administration was initially circumspect about Israel's claim that North Korea was helping Syria, and decided against an immediate response because of negotiations aimed at persuading Pyongyang to ditch its nuclear programme.

However, the US is believed to have provided Israel with some corroboration of the original intelligence before Israel went ahead with the raid, the Post said.

The operation reportedly was carried out under such strict secrecy that the pilots flying air cover for the attack aircraft did not know the details of the mission and the airmen who conducted the attack were briefed only after they were off the ground, the paper said.

The Israeli attack came three days after a North Korean ship docked at the Syrian port of Tartus carrying a cargo officially listed as cement.

The ship's contents remain in dispute, with some Israeli sources suggesting it was nuclear equipment. Others say the ship was carrying missile parts, while some have said the vessel's arrival and the attack were merely coincidental.

There is also scepticism about the intelligence that prompted the attack, as Syria has actively pursued chemical weapons in the past but not nuclear arms.

The incident remains the subject of much conjecture because, unlike after its destruction of an Iraqi nuclear reactor in 1981, Israel has made no official comment about the attack and the Israeli media has been under strict censorship. For its part, Syria has made only muted protests, and Arab leaders have kept quiet.

Meanwhile, North Korea and Syria today held high-level talks in Pyongyang. The talks were between Choe Tae Bok, the secretary of the central committee of the North's ruling Workers' party, and Saaeed Eleia Dawood, the director of the organisational department of Syria's Ba'ath Arab Socialist party, the official Korean central news agency reported.

The two sides discussed ways of improving friendship and cooperation, and other issues of bilateral interest, KCNA said.

The meeting is bound to increase speculation about the exact nature of relations between the two countries. Both have denied reports of nuclear cooperation.

Andrew Semmel, the acting US deputy assistant secretary of state for nuclear nonproliferation policy, said last week that North Koreans were in Syria, and that Syria may have had contacts with "secret suppliers" to obtain nuclear equipment.

As the latest details emerged about the Israeli raid, China said talks between North Korea and regional powers about ending Pyongyang's atomic weapons programme would resume in Beijing next week.

The announcement came a week after the lead US negotiator, Christopher Hill, said he expected to attend the talks despite the reports that Syria might have received North Korean nuclear help.