Outspoken T-Mobile US CEO John Legere (pictured) has taken aim at reports of an exclusive arrangement between rival AT&T and Amazon for the debut of the online retailer’s first smartphone.

“Phew @amazon doesn’t know what they just signed up for. Remember the Facebook phone? #Yikes”, tweeted Legere, no stranger to abrasive comments about competitors.

The AT&T link-up was reported by The Wall Street Journal. The official launch of Amazon’s smartphone is later today.

Last year AT&T had a bad flop with the HTC First – a smartphone with Facebook Home pre-installed that disappointed with its sales.

Legere also attacked the new alliance for being anti-competitive: “When #big (@AT&T) and #bigger (@amazon) get together, the industry feels a whole lot smaller.”

“The odd thing is, big + bigger = fewer options for customers”, he followed up with another tweet.

Amazon already has a relationship with AT&T which provides connectivity for its Kindle tablet and e-readers, offered to users with unlimited data. Users also pay a subsidised price for the tablet and e-reader. The model is supported by their purchase of digital content. However, it is unclear if Amazon will deploy a similar business model for its smartphone.

Back at CES in January, AT&T unveiled a sponsored data service offering where usage for specific content and apps was charged to a sponsoring company.

Meanwhile the Financial Times reports that Amazon is in talks with European operators about similar partnerships. Sources say the online retailer has spoken with O2 and Vodafone in the UK.  Like AT&T, Vodafone has supplied connectivity to the Kindle.

Amazon’s smartphone will feature a display that responds to eye movement and can showcase 3D images, suitable for games as well as providing all-round views of goods for sale on the retailer’s site.

Legere also flagged up the latest instalment of its Uncarrier strategy in which it has sought to position itself as the outsider in the US mobile industry. It will be announced later today.