UNITED NATIONS - A U.N. inquiry into the murder of former Lebanese Prime Minister Rafik al-Hariri will take air samples from five Middle East nations after it found the suspected suicide bomber grew up in a polluted city.

Belgian prosecutor Serge Brammertz, the head of the investigation, said in his seventh report to the U.N. Security Council on Thursday that he was unlikely to meet a current June deadline and would need more time.

Brammertz has previously reported that the suspected suicide bomber -- who killed Hariri and 22 others on February 14, 2005 -- had not spent his youth in Lebanon, but had likely spent two or three months there before his death.

"The commission can now add that the man had significant exposure to lead pollution in an urban environment up to the age of about 12, and that such exposure was low during the last 10 years of his life, possibly indicating that he lived in a more rural environment during this period," the report said after tests on remains of the bomber.

It said that to continue this line of inquiry 112 samples had been collected from 28 locations in Lebanon and Syria.

"Over the coming weeks, it will collect samples in three other countries in the region and further countries are identified for another series of sampling missions," it said.

Syria, whose officials had been implicated by Brammertz's predecessor in the Hariri assassination, was cooperating with the commission, the report said.

Syria denies involvement in the Hariri slaying, which took place after the former prime minister accused Damascus of meddling in Lebanese politics. Street protests in Lebanon after the killing prompted Syria to withdraw forces that had been in the country for 22 years.

The government and the U.N. Security Council have approved plans to establish a special court to try Hariri's killers, over objections from the Hezbollah-led opposition and from Lebanon's pro-Syrian president, Emile Lahoud.

The evidence Brammertz collects will be submitted to the court. The Security Council has also asked Brammertz to look at 16 other politically motivated cases, including the November 21 assassination of Lebanese Industry Minister Pierre Gemayel. -Reuters