Swiss inspections group SGS on Thursday denied any responsibility for security at the site in southern Iraq where radioactive material used to test pipes at an oil field in southern Iraq disappeared last year.
"The site where these operations are conducted is fully secured and guarded by security guards under the responsibility of the owner of the site. SGS does not assume any responsibility for the site security and does not control accesses," it said in a statement on Thursday, adding many contractors used the site.
Iraq is searching for "highly dangerous" radioactive material whose theft last year has raised fears among Iraqi officials that it could be used as a weapon if acquired by DAESH.
SGS said its Turkish unit had been hired by US group Weatherford to perform the tests, which use what it called a low-level radioactive source.
"When not in use, the equipment and radioactive source are stored in a secured bunker designed for that effect and provided by Weatherford. The disappearance of the equipment occurred while the equipment was stored in the Weatherford bunker," it said, adding the loss was discovered on Nov 3.
Its Turkish business immediately notified Iraqi authorities and cooperated fully with the investigation, it said.
Weatherford has also said that it was not responsible or liable for the theft. "We do not own, operate or control sources or the bunker where the sources are stored," it said on Wednesday.