BEIRUT/LONDON, July 31 (Reuters) - A sanctions-hit tanker is leaking ​oil off the coast of Oman and the spill has spread in recent days, increasing ‌concern about possible environmental damage to coastal areas, according to an analysis of satellite imagery and shipping specialists.

The Caroline Bezengi took Russian oil on board at the Black Sea port of Novorossiysk before leaving for its most recent voyage, ship tracking ​data shows.

It first reported difficulties on June 8 off the southern Yemeni port of Mukalla, two maritime ​security sources said, adding that initial assessments indicated that a blast occurred onboard.

A ⁠satellite image from July 28 shows a dark slick in the water near the vessel and lighter ​patches north of al-Qibliyyah island, which lies close to Oman's coast and is part of a protected marine ​area.

"The darker oil slicks indicate that at least one of the hulls of the crude oil storage ship seems now to be breached, and the ship is leaking crude oil," Wim Zwijnenburg, a remote-sensing specialist with the Dutch peace advocacy ​organisation Pax, said after reviewing the imagery.

The area's monsoon season, which usually peaks in July and August, ​can bring severe weather conditions that could rapidly spread the crude oil, Zwijnenburg added.

Reuters ‌verified ⁠that the ship shown in recent satellite imagery is the Caroline Bezengi by its deck structures and paint, which matched archive imagery of the vessel, which is subject to European Union and UK sanctions for alleged involvement in carrying Russian fuels.

Its owner, listed on shipping databases as Shanghai-based Rentoor Shipmanagement, could not be ​reached for comment.

Oman's Transport, Communications ​and IT Ministry did ⁠not respond to a request for comment.

An oil tanker specialist who reviewed the satellite images said the vessel was likely to be listing. Other maritime sources ​warned that it could break up at some point.

"At present the vessel is ​not broken ⁠up. Discussions by authorities are ongoing on addressing safety and environmental risks," a spokesperson for the U.N.'s International Maritime Organization (IMO) said earlier this week, adding it was monitoring the situation closely.

Russia uses aging, often poorly maintained tankers ⁠in its ​so-called shadow fleet to circumvent Western sanctions on its oil ​exports.

It is not clear whether the blast damage on the vessel was caused by a possible attack by Ukraine, which has targeted Russian-related ​tankers, or stemmed from the conflict in the Middle East.