• Greenpeace reports five larger oil slicks in the Strait of Hormuz, reaching the Iranian coast near protected areas around Qeshm Island and the Omani side, potentially originating from the Riesco tanker.
• The tanker Caroline Bezengi, part of Russia's shadow fleet and subject to EU sanctions, ran aground along Oman's southern coast, with the visible area of the oil slick estimated to have expanded from 400 to 600 square kilometers.
• US military attacks on tankers linked to Iran, along with Iran's repeated attacks on vessels in the region, have made it difficult to pinpoint the exact source of pollution due to limited transponder data, as Greenpeace notes further oil slicks spreading along Oman's coast.

Satellite images of the Strait of Hormuz now show five larger oil slicks, according to an assessment issued late on Monday by the environmental organization Greenpeace.

The pollution has reached the Iranian coast near protected areas around Qeshm Island, Greenpeace Germany said in a statement. The island is home to large mangrove forests, among other things.

One of the oil slicks is also visible on the Omani side of the Strait of Hormuz, it added. The rugged coastline there is considered an important bird resting area.

Further oil slicks in the region could originate from the Riesco tanker. "This could indicate that the vessel has sunk and is continuing to leak oil," Greenpeace wrote, referring to what it merely described as a possible scenario.

The US military said last week it had attacked the Riesco and other tankers linked to Iran. Iran has also repeatedly attacked several vessels in the region. Linking the pollution to specific ship attacks in the region is often difficult, partly due to limited transponder data.

A further oil slick is also spreading along Oman's southern coast, according to Greenpeace. The tanker Caroline Bezengi - attributed to Russia's so-called shadow fleet and subject to EU sanctions - ran aground there.

"On September 11, the visible area was estimated at around 400 square kilometres, and on September 12 at approximately 600 square kilometres," Greenpeace wrote, citing a preliminary estimate.

The reason for the expansion is currently unclear, with possible causes including further damage to the vessel as well as changed weather and sea conditions.