Apple's iPhone 5S could be available in a new gold colour, and could have a 128GB option, evidence suggests.

Last week, KGI analyst Ming-Chi Kuo, who has an impressive track record when it comes to predicting Apple launches, suggested that the next-generation iPhone could be available in a new gold colour, and could also have a 128GB option.

Since his prediction, which was reported by Apple Insider, photographs of what appears to be a gold iPhone 5S casing have emerged, and a German retailer has added a new 128GB iPhone model to its inventory, adding evidence to the theory.

See: iPhone 5S release date, rumours and leaked images

French blog MacBoutic published the photographs of what is allegedly a gold iPhone 5S rear shell, claiming that Apple's expected 10 September event will see the new colour option unveiled.

TechCrunch's MG Siegler has also said that he's heard from "multiple sources" that there will be a gold iPhone, adding to the speculation.

This is not the first time we've seen gold components leaked on the web. In May, a gold SIM tray was discovered, suggesting that the new colour was on its way. In June, further gold parts were leaked online.  

Meanwhile, German blog Macerkopf has reported that a retailer has added a 128GB iPhone to its inventory. Apple has already introduced a 128GB version of its iPad, so it is possible that the company will chose to do the same for its iPhone, too.

Kuo's latest prediction also suggests that the iPhone 5S will have an A7 chip with 1GB of RAM and increased speed.

He also reiterates the rumours that the iPhone 5S will have an improved camera and dual LED flash, as well as a fingerprint sensor built-in to a sapphire glass Home button.

He says he doesn't expect the iPhone 5S to have NFC, despite some recent reports suggesting otherwise.

See also:

Leaked iPhone parts roundup: iPhone 5C, iPhone 5S

Apple releases iOS 7 beta 6, golden master coming 5 September?