India said Thursday there have been "intensive discussions" but no progress toward gaining the release of an Indian oil tanker detained by Iran for the past week.

The vessel, belonging to Shipping Corp. of India, was carrying crude oil from Iraq to India. Iranian naval authorities detained the ship Aug. 13 in the Persian Gulf, saying it was polluting Iranian waters.

India, the world's fourth-largest oil importer, has significantly reduced its import of crude oil from Iran as U.S. and European sanctions made it difficult to ship oil from the Persian Gulf nation.

India's Foreign Ministry, in a statement published Thursday by the Kuwait News Agency, said, "Regarding this incident of the Indian ship, we have constantly been in touch with Iran on this issue, and despite intensive discussions, we have not yet made any progress."

The ministry's statement said the matter "is being pursued vigorously" by the Indian embassy in Tehran and asked for patience "as we work towards a successful outcome in a delicate situation."

An Indian team dispatched to Bandar Abbas port, where the tanker is being held, said it detected no pollution or oil leakage by the vessel.

"Our officials including the surveyor from (the) Indian Register of Shipping have completed the inspection of the tanker and come up with a report that no pollution whatsoever or oil leakage was caused by it," a senior Shipping Corp. of India official told Press Trust of India Tuesday.

The ship was built in 2004.

An Indian shipping ministry official said a meeting scheduled in New Delhi Wednesday between Indian officials and Iranian diplomats had been postponed, the Journal reports.

A Shipping Corp. of India executive whose name was not reported told the Journal Tehran had asked for "guarantee money" from India that could be used to pay compensation for the environmental damage caused by the ship. But an Iranian official said the ship's insurer, based in Britian, could not provide the guarantees because of the EU sanctions.

Iran's embassy in India, in a statement issued Friday, said the holding of the ship was "purely a technical and nonpolitical issue."

The embassy said the vessel was detained following a warning from the Marine Emergency Mutual Aid Center, which is a regional intergovernmental organization concerned with marine pollution.

A senior official from India's Shipping Ministry told PTI last week "it It was alleged that it (the ship) caused pollution on July 30th but the fact remains that the tanker was not carrying crude on that date."