A "worsening security outlook" in Libya prompted fertilizer giant Yara International to write down the value of its stake in the loss-making Lifeco nitrogen plant, which is facing a "challenging financial situation".
Yara, the world's largest nitrogen fertilizer group, slashed by $112m to $18m the book value of its stake in the Lifeco joint venture, citing the "worsening security outlook in Libya".
"The political and security situation in Libya has worsened rapidly, and may deteriorate further over the next year," Yara said.
There was a "high likelihood of a further deterioration in 2015 of the operating ability" of the operation, which has thanks to Libya's unrest struggled to gain sufficient supplies of the raw materials.
Yara flagged "an already-challenging feedstock and financial situation for the joint venture", which has run in the red since 2011.
The group added that it was "evaluating the operation of the plants on an ongoing basis in cooperation with the other partners, in order to protect the employees as well as the assets.
Yara owns 50% of Lifeco, with Libyan government agencies holding the balance. The plant produces urea and ammonia from natural gas, supplied by the state-owned national oil company.
Production at Lifeco was stopped last year thanks to blockade by a local militia group, with output resuming gradually to reach 50% of capacity in the second half of 2014.
Lifeco contributed a net loss of NOK189m to Yara's results last year – a fourth successive year of losses, which have totalled NOK574m, equivalent to $73m at current exchange rates.
Libya has seen the set up of two rival parliaments, both claiming legitimacy from the 2011 overthrow of former leader Colonel Gaddafi, which are currently locked in UN-brokered talks to agree on power.
Both governments claim ownership of the country's natural resources, leading to fighting over control of petrochemical facilities.
The country is also under threat from Islamist forces, which have in the past targeted western owned resource extractors.
Skirmishes between Islamist insurgents and the army broke out in the outskirts of the capital Tripoli this weekend.