Yemen’s Houthi rebels have rejected, for the second time, a United Nations request to allow inspectors to board a rusting oil tanker moored off the country’s Red Sea coast.

The international community has repeatedly warned the corrosion of the FSO Safer, which is carrying 1.1 million barrels of oil, risks an explosion which would cause an environmental and humanitarian catastrophe.

Yemen’s internationally-recognised government has called on the UN to take tougher measures against the rebels saying the “lenient” approach must stop.

“The Houthis have behaved arrogantly because of this approach. The international community should pressure the Houthis to either empty the ship or subject it to immediate maintenance,” Salem Al Khanbashi, Yemen’s deputy prime minister, told Arab News.

The tanker is anchored near the coastal city of Hodeidah, the entry point to most of the country’s humanitarian supplies.

The Iran-backed rebels accuse the Saudi-led coalition, that is fighting in Yemen on behalf of the government, of exploiting the UN’s attempt to inspect the ship.

They want the assessment and repair to happen in one visit but the UN says it needs to inspect the tanker before deciding what kind of repairs it needs and if the oil should be extracted.

The Houthis also claim that some of their own experts must board the ship alongside UN inspectors. One of the issues raised by the Houthis is who would get the proceeds of selling any viable oil stored in the ship.

The government accuses the rebels of seeking to extract concessions from the international community as the ship continues to degrade.

The UN has said that the tanker could spill four times as much oil as during the 1989 Exxon Valdez disaster off Alaska.

Saudi Arabia told the United Nations last month that oil spots were seen in the sea near the tanker and again warned that a leak of crude would not only devastate the Yemeni coast but impact countries up and down the Red Sea.