BSS/AFP) - An oil spill from a tanker that ran aground off Oman has reached the coastline, state media reported, while monsoon winds were obstructing containment efforts, the United Nations` maritime agency said on Wednesday.

An AFP investigation previously found that the ship had been stranded for weeks near Oman`s Al-Qibliyyah island after it was damaged by explosions.

The Oman News Agency (ONA) quoted the country`s environment authority as saying that "today`s monitoring results showed that some beaches in the Ras Madrakah area were affected by oil pollution".

The Indian Ocean town sits more than 200 kilometres (125 miles) from Al-Qibliyya.

A spokesperson for the UN`s International Maritime Organization said it was "closely monitoring" leakage from the crude oil tanker Caroline Bezengi.

The vessel grounded off Oman on 30 June and is currently around 22 nautical miles off the Omani coastal town of Sharbithat, the spokesperson said.

They added that oil was drifting offshore to the northeast of Al-Qibliyyah, with some reported as reaching the mainland, even as "the seasonal monsoon has limited access to the vessel and delayed salvage operations".

Oman said on Monday it was working to contain the spill, which had affected roughly 390 square kilometres (150 square miles), according to the most recent analysis from the country`s environment agency.

The slick was concentrated around the Hallaniyat archipelago off the southern coast, where a marine reserve was established last year to protect sensitive ecosystems home to diverse marine life, including rare sea turtles.

On Wednesday, the ONA reported that "a coastal stretch of up to 40 kilometers in the (Ras Madrakah) area is expected to be affected".

The southern beaches of Masirah Island, spanning 10 to 20 kilometers, could be contaminated "in the coming hours", it said.

Hormuz slick -

Omani authorities have not yet identified the cause of the spill.

But British maritime security company Vanguard told AFP last week that the tanker was hit by explosions in early June as it sailed off the coast of Yemen, causing water to enter several sections of the vessel.

Advocacy groups Greenpeace and PAX told AFP that the spill was on the verge of causing an "environmental disaster", saying the tanker was carrying around one million barrels of crude.

The ship is believed to be part of Russia`s "shadow fleet" used to circumvent Western sanctions on its oil exports.

The fleet includes ageing vessels that have faced criticism over maintenance, insurance and safety standards.

Tankers have been frequently targeted in the Gulf region in recent months as the United States has exchanged fire with Iran and its allied proxies.

In Iran, media reported on Wednesday that an oil slick in the Strait of Hormuz had reached the island of Qeshm, affecting beaches and an environmentally sensitive mangrove forest.

State news agency IRNA said the slick had affected areas on Qeshm`s southern coast, as well as parts of the smaller neighbouring island of Hengam.

TankerTrackers, a US-hosted website that monitors shipping movements worldwide, said the spill seemed to derive from the Iranian attack on bulk carrier Minoan Pioneer, carried out in Omani waters on August 3.

"The spillage then drifted across the strait over to Iran," TankerTrackers said.

Iran`s foreign ministry spokesman Esmaeil Baqaei said pollution had been observed at three locations and on the sea surface, adding that its source seemed to be a "foreign bulk carrier", without specifying.

"Any party that benefits from commercial shipping through the Strait of Hormuz is legally and morally obligated to take action to compensate for and remedy the environmental damage caused to the Persian Gulf and the Gulf of Oman," he said.