Western powers have called on forces loyal to Libya’s powerful general, Khalifa Haftar, to leave the oil ports they have seized from the country’s UN-backed Government of National Accord (GNA).

Haftar’s forces have captured the Mediterranean ports of Ras Lanuf, Es Sider, Zueitina and Brega over the past two days.

“We call for all military forces that have moved into the oil crescent to withdraw immediately, without preconditions,” the US, France, Germany, Italy, Spain and Britain said in a joint statement on Monday.

The Western countries also denounced the assaults on the ports, warning that they will seek a UN Security Council resolution aimed at preventing the “illicit” exports of oil from Libya.

The fighters, who support the rival government based in east Libya, had attempted to sell oil with the approval of the government and the National Oil Corporation in Tripoli.

The Western powers further stressed that Libya’s oil infrastructure, production and export must remain under the control of the corporation acting under the authority of the GNA.

Meanwhile, Martin Kobler, the United Nations special representative and head of the UN Support Mission in Libya (UNSMIL), expressed “grave concern” over the battles around the oil ports.

“Attacks on the oil terminals further threaten the stability and lead to a greater division of the country,” said Kobler. “They further restrict the oil exports and add to people’s suffering.”

He also urged Haftar’s forces to refrain from further military escalation.

The North African country has had two rival governments since mid-2014, when militants overran the capital and forced the parliament to flee to the remote east.

The two governments reached a consensus on the formation of the GNA in December 2015, after months of UN-brokered talks in Tunisia and Morocco to restore order to the country. Libya, however, continues to be gripped by political strife and violence.

Libya has been the scene of increasing violence since 2011, when long-time dictator Muammar Gaddafi was toppled from power after a NATO military intervention. His ouster created a huge power vacuum in Libya, leading to chaos and emergence of numerous militant groups.