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Apple CEO Tim Cook is expected to reveal the iPhone 6s on 9 SeptemberReuters

Apple is planning to hold a media event on 9 September where it will announce the iPhone 6s and 6s Plus, according to several sources familiar with the company's plans. This is a day later than expected, thought to be because of Labor Day, the US public holiday which falls on 7 September.

This pushes the event to 9 September, a day later than Apple's favoured day to announce new products. Despite this, we still expect to see the smartphones go on sale on 18 September. Pre-orders are likely to open a week earlier, on 11 September.

Speaking to BuzzFeed News, several unnamed sources "familiar with Apple's plans" say the event will take place on 9 September, exactly a year to the day the iPhone 6 and 6 Plus were announced. The date also neatly coincides with iOS 9, which will be the software running on the new handsets, and their processor, likely to be called the A9.

Alongside two new iPhones – expected to look identical to the current line-up, but feature new Force Touch displays – Apple is said to be preparing a new iPad with a bigger screen. Thought to be called the iPad Pro, it will measure 12.9in, around 30% larger than the iPad Air 2.

But despite numerous sources claiming the iPad Pro is ready for its public unveiling, BuzzFeed says its arrival on 9 September "seems to be a wildcard, still". More likely is the announcement of a major update for the Apple TV set-top box. According to insiders, the new product was meant to arrive at Apple's WWDC event in June but was delayed and now looks set to appear with the new iPhones.

As has been widely reported over recent weeks and months, the new Apple TV is claimed to have a new design, be powered by Apple's A8 mobile processor – as used by the iPhone 6 and 6 Plus –have increased storage and a new operating system with Siri voice support. A new and "drastically improved" remote is also tipped by sources of BuzzFeed News, featuring a touchpad for navigating the Apple TV's new software. It will reportedly get its own App Store, paving the way for developers to create apps and games to run on your television.