A Syrian complex bombed by Israel bore features that would resemble those of an undeclared nuclear reactor and Syria must cooperate more with UN inspectors to let them draw conclusions, a watchdog report said on Wednesday.

According to the report, nuclear inspectors took samples from the site, which was bombed by Israel Air Force jets in September 2007, on their lone visit in June 2008. Lab results showed traces of uranium, according to the report, which stressed that the traces had undergone chemical processes.

The report states that the high number of water pumping installations was sufficient to serve a nuclear facility that would be built near the Euphrates River.

The International Atomic Energy Agency report stresses that Syria refuses to produce documents in relation to the site as it is required to do. The report accuses Syria of denying access for further inspections to the site as well as three other locations believed to be tied to the construction of the suspected reactor.

The report explicitly states the site was bombed by Israel even though Israel has never confirmed this publicly. An American intelligence report, which was released earlier this year and cited photographs which suggested the building resembled a North Korean nuclear reactor, also did not mention Israel as the party which carried out the bombing.

Obtained by Reuters, the report said "significant" amounts of uranium particles were found at the site by inspectors who checked it in June but it was not enough to prove a reactor was there and further investigation was needed.

"While it cannot be excluded that the building in question was intended for non-nuclear use, the features of the building, along with the connectivity of the site to adequate pumping capacity of cooling water, are similar to what may be found in connection with a reactor site," the IAEA stated in the report.

"Syria has not yet provided the requested documentation in support of its declarations concerning the nature or function of the destroyed building, nor agreed to a visit to the three other locations which the Agency has requested to visit," the report said.

The confidential IAEA report said the UN watchdog would ask Syria to show debris and equipment it whisked away from the site after the September 2007 Israeli air raid. Washington says the target was a nascent reactor meant to produce plutonium for atomic bombs. Syria denies this.