The International Monetary Fund has suspended its loan to Yemen indefinitely, citing a "host of uncertainties" stemming from the escalating unrest in the country.

In September, the IMF approved a $552.9 million US ($726.2 million NZD) line of credit to help highly impoverished Yemen maintain economic stability and promote inclusive growth. The first installment of the three-year loan, nearly $74 million US, was made available immediately.

The next disbursement was expected in the first quarter of 2015 after an IMF review of the loan-supported reform program.

"Given the host of uncertainties surrounding Yemen at the moment, the first review... is postponed until the situation clarifies," IMF spokesman William Murray said at a regularly scheduled news conference.

The security situation in Yemen has deteriorated sharply amid attacks by Shi'ite Huthi rebels, which have grabbed power in some areas and forced the president to flee the capital.

Saudi Arabia and its Sunni Muslim partners in the Gulf launched air strikes against the Huthi rebels late Wednesday, spurring a warning from regional Shi'ite rival Iran.

Murray said he could not say when the situation will clarify enough to resume the loan program or estimate the economic impact of the crisis in the region.

"One of our biggest concern in Yemen is the impact on the poorest there," he said.
The spokesman said that he was unaware of any "recent contacts" between the IMF and the Huthi rebels.

In mid-March, the World Bank announced its suspension of activities in Yemen due to the deepening crisis.