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Electric car-maker Tesla quarterly revenues have more than doubled helped by higher deliveries of its upmarket vehicles but its losses also grew.

The company reported revenue of almost $2.8bn (£2.1) in the three months to 30 June, up from $1.3bn during the same period last year.

Losses increased to $336m, compared with $293m last year.

But investors were encouraged by the firm's prospects and shares rose by more than 7% in after-hours trading.

Tesla, which also has a solar energy division, said almost $2.3bn in revenue during the quarter came from the firm's automotive unit - roughly the same as in the previous quarter, but 93% higher than the same period in 2016.

However, the company's costs, including for research and development and sales, also rose contributing to the 15% rise in its losses for the quarter.

Tesla is preparing to ramp up car production, as it rolls out its most affordable ($35,000) car yet for the mass market.

Tesla told shareholders it expects revenue to grow "significantly" in the second half of the year, while expenses hold steady.

The firm delivered more than 47,000 of its earlier high-end Model S and Model X cars in the first half of 2017, growth of more than 50% from the prior year.

Since it rolled out its latest car, Model 3, to a small group last week, it is averaging more than 1,800 reservations for the car a day, adding to the more than 400,000 orders that are already placed.

So far, demand for the new make isn't cannibalising interest in the older models, chief executive Elon Musk added.

"July was one of our best months ever," he said. "Who knows if this will continue, but all indications are that it will, so that's very exciting."

The firm hopes to make 5,000 of the Model 3 cars per week by the end of 2017. The firm plans to eventually make more than 500,000 a year at its Fremont factory - or about 10,000 per week.

Analysis: Dave Lee, BBC North America technology reporter, San Francisco

Elon Musk's company is spending big to make sure the target of 50,000 Model 3s by the end of the year isn't missed.

Production of the "affordable" ($35,000) car being on schedule is critical to the company's future - perhaps even the future of Mr Musk himself as he seeks to court even more money for outlandish projects.

That's why Tesla burned through over $1bn in the last quarter, as analysts had anticipated.

There are half a million pre-orders for the Model 3, and Mr Musk said the company is facing "manufacturing hell" to get them all made.

According to the latest projections, Tesla thinks it's on course to keep customers happy. Any wavering on that goal would send the stock price south. For now, things are on track.