(CNN) - Apple has recalled two types of plug adapters and asked customers to stop using them because of a risk of electric shock.
The company said on Friday that it has recalled the AC wall plug adapter sold with Macs and some iOS devices between 2003 and 2010, and a three-pronged plug included in the World Travel Adapter kit.
The affected plugs were shipped in the United Kingdom, Singapore and Hong Kong, it said in a statement.
"In very rare cases, affected Apple three-prong wall plug adapters may break and create a risk of electrical shock if touched," it added.
The statement said: "Apple is aware of six incidents worldwide." It did not clarify how many people had received electric shocks. Apple said the recall was voluntary and that customers can exchange affected plugs.
The affected three-pronged plug adapter is white, with no letters on the inside slot where it attaches to the main Apple power adapter, the statement said. Apple USB power adapters are not affected.
The company released information to help customers to identify the affected models.