Apple has rolled out a trade-in programme in its retail stores in the US for older iPhone models, as it prepares for the launch of a new smartphone version.

As part of the programme, the iPhone maker will offer its customers a credit for their old phones to be used for buying a new model.

The program reportedly enables iPhone owners to exchange non-water damaged devices in good working order, for between $120 and $250 or so.

Apple spokeswoman Amy Bessette said in a startement that Apple Retail Stores are launching a new programme to assist customers who wish to bring in their previous-generation iPhone for reuse or recycling.

"In addition to helping support the environment, customers will be able to receive a credit for their returned phone that they can use toward the purchase of a new iPhone, Bessette said.

Apple has also collaborated with Brightstar, a firm that purchases and resells used electronics, assist in executing the trade-in programme.