A Romanian oil company says one of its rigs stationed in the Gulf has come under fire from Iranian troops.
A spokesman for the firm GSP said Iranian troops had seized the rig after firing from a nearby ship, and GSP lost contact with its 26 workers there.
Radu Petrescu said the Orizont rig had been moored near Kish island since October 2005.
GSP operates two rigs off Kish. The other rig is reported to have been involved in a legal dispute in Iran.
It is unclear whether the incident on Tuesday was related to that dispute.
The shooting reportedly happened as the rig was being taken outside Iranian waters for a mandatory overhaul.
The rigs are operated under a deal signed between Petrom, GSP and Dubai-based Oriental Oil Co.
A statement on GSP's website, signed by company president Gabriel Comanescu, said the Iranian action was a "flagrant breach of all the international rules".
It said that since Monday, Iranian military helicopters and ships had been "trying to intimidate the Romanian crew aboard the rig".
Then early on Tuesday "an Iranian military cutter boat opened fire against the Orizont rig, in the stern crane" and Iranian troops occupied the rig, the statement said.
"We do not know if anyone is hurt," it added.