Ghana’s currency weakened to an all-time low as a surprise interest-rate increase failed to stem the worst currency decline in Africa.

The cedi dropped as much as 1.7 percent to 3.9550 per dollar, before paring losses to trade at 3.9150 as of 4:25 p.m. in Accra, the capital. That extended its 2015 slide to 18 percent, the most among 24 sub-Saharan African currencies monitored by Bloomberg.

The Bank of Ghana raised its benchmark rate by 1 percentage point to 22 percent. All eight economists surveyed by Bloomberg predicted the rate would stay unchanged. The government is struggling to keep debt under control, prompting authorities to turn to the International Monetary Fund for emergency aid of about $900 million to help finance the fiscal gap and bolster the currency.

Demand for dollars to pay for imports and speculative dollar purchases by companies expecting further cedi weakness is fueling the currency’s drop, Celeste Fauconnier, an Africa analyst at FirstRand Ltd.’s Rand Merchant Bank in Johannesburg, said by phone. The rate increase “will not take away from the fundamentals that will push the depreciatory trend toward the end of the year,” she said.

The IMF agreed to lend Ghana cash in a three-year program that includes targets for curbing government wages and narrowing the budget deficit from last year’s 9.3 percent of gross domestic product. West Africa’s second-biggest economy is battling 24-hour power blackouts and is growing at the slowest pace in two decades. Lost Confidence

The currency’s weakness is because of the “mismanagement of the economy,” Michael Otu Fiaw, a research analyst at NDK Asset Management Ltd., which manages 420 million cedis ($107 million) in pension and corporate funds, said by phone. “People have lost confidence in the cedi.”

The government is optimistic it can meet its budget deficit target of 7.5 percent of GDP for this year, Finance Minister Seth Terkper said in an interview on Tuesday. The shortfall was an average of about 10 percent in the past three years.

Ghana is the world’s second-largest cocoa producer after Ivory Coast. Oil is the country’s biggest export by value after gold and the nation produces about 100,000 barrels a day from its Jubilee field that’s operated by Tullow Oil Plc. The government is forecasting 3.9 percent growth this year, little changed from 4 percent in 2014.

A weaker currency has boosted inflation to 16.8 percent in April. The government’s year-end inflation target is 11.5 percent.

The currency’s slide “is one of the factors that the committee considered,” Bank of Ghana Governor Kofi Wampah told reporters in Accra. “Risks to both inflation and growth are elevated, but tilted more to inflation. It was therefore noted that a further moderate tightening, complemented with sustained fiscal consolidation efforts could rein in inflation and inflation expectations.”