Apple has been sued by iPhone customers in at least three complaints related to antenna problems on its newest iPhone 4 model.

Apple launched the iPhone 4 last week but the launch was also plagued by complaints from some customers about poor call reception on the device when they held it in a certain way. Social networking site Twitter was full of chatter, with numerous tweets on the reception problems.

However, the issue does not seem to have hurt iPhone sales so far. Apple sold 1.7 million new iPhones in the first three days.

A class action filed Tuesday in the U.S. District court for the Northern District of California against Apple and AT&T Inc -- the iPhone's exclusive wireless carrier in the United States -- includes allegations of fraud by concealment, negligence, intentional misrepresentation and defective design.

The company responded to user complaints last week by saying the antenna performance of every wireless phone is impacted in some way by the how it is held, depending on where the antenna is located.

In another purported class action complaint filed on Wednesday against Apple and AT&T, in the U.S. District Court for the District of Maryland, Kevin McCaffrey and Linda Wrinn said they were sold "defective" iPhone 4 units, which drop calls and data service, "when held in a manner consistent with normal wireless phone use."

The cases are 10-02862 Goodglick v. Apple Inc, and 10-01776 McCaffrey et al v. Apple Inc. et al.