BlackBerry’s new square-screen smartphone, Passport, will go on sale for $599 without subsidies in the US, a price that is designed to undercut rivals, according to an interview with CEO John Chen in the The Wall Street Journal.

The phone debuts on 23 September.

Looking at comparable models from rivals, Chen said Passport should be priced in the $700 range but he said: “I figured that to try and get the market interested, we’re going to start a little lower than that.”

The pricing will vary in some other countries, depending on taxes and tariffs, he said.

The company has been talking up its new square-screen smartphone, claiming that the 4.5-inch display offers a superior viewing experience than rivals with 5-inch screens because of the additional width that comes with its distinctive design .

But Passport is facing some tough competition even with its price advantage, not least the new iPhone 6 which sells for an unsubsidised $649, or the iPhone 6 Plus which weighs in at $749. And then there is the Samsung Galaxy S5 which costs about $650 at launch earlier this year.