Ghana’s cedi weakened to a record as importers bought dollars amid speculation a surprise interest-rate increase last month won’t be enough to stem the currency’s decline.

The cedi fell as much as 1.6 percent to 4.1050 per dollar before trading 1.2 percent weaker at 3:59 p.m. in Accra, the capital. The currency of the world’s second-biggest cocoa producer has plunged 21 percent this year, the worst performance among 24 African currencies monitored by Bloomberg.

“We see increased demand for dollars from commerce and the pharmaceutical industry to pay bills,” Anthony Kofi Asare, head of treasury at GCB Bank Ltd., Ghana’s biggest lender by branches, said by phone on Monday. “There is an element of speculation.”

Ghana’s central bank unexpectedly increased its policy rate by 100 basis points to 22 percent on May 13 to bolster the cedi and combat inflation.

The central bank sold from $300,000 to $500,000 each to some lenders on Monday, Nana Yankson, a currency trader at Accra-based Universal Merchant Bank Ltd., said by phone on Monday.