Dog lover Andy Murray has announced a new business investment in a device that allows pet owners to track their animals and keep them safe.

The tennis ace has put some of his estimated £48 million fortune into Dog Tracker Nano, a live tracking device which allows owners to monitor their dog's activity, fitness and location.

The business is one of a number of British start-up firms to receive a boost from the Scot, who has two terriers, Maggie May and Rusty, and has often spoken about his love for dogs.

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Murray has also invested in a London-based mobile 'beauty on demand' service and a navigation device for cyclists.

The investments have been made through equity crowdfunding platform Seedrs, where he already has investments in 12 other new businesses.

Murray said: "Giving recognition and support to British entrepreneurs is really important to me, especially those who are the driving force behind growth-focused businesses.

"Every one of these entrepreneurs is passionate and dedicated to succeeding and I’m excited to have invested in their future growth."

The move sees the tennis champion, who has his sights set on a fifth victory at Queens this month, expand his growing business empire, adding to his management company 77 and luxury Scottish hotel Cromlix near his hometown of Dunblane, acquired by the 28-year-old in 2013 for around £2m.

The navigation device for cyclists, Beeline, allows cyclists to navigate by informing them of the direction and distance to their destination. The firm successfully raised over £500,000 in under a week from over 350 investors on Seedrs, quickly exceeding its fundraising target of £400,000.

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While Blow LTD, the mobile beauty service, has raised more than £1.1m from over 210 investors, including Unilever Ventures and the founder of online retailer ASOS.

Jeff Lynn, CEO and co-founder of Seedrs, said: "It’s great to see Andy supporting entrepreneurs so actively on Seedrs by investing in another three businesses today. "Andy is a great example of an investor who understands early stage investment and the importance of building a diverse investment portfolio aligned with a wider investment strategy.

"Seedrs was named the most active investor in private companies in the UK last month, and our continued growth and leading position in the market are testament to our reputation and the support from people like Andy."

Murray is one of Britain's wealthiest sportspeople and was last year named as fourth richest sportsperson in the UK.

He has numerous sponsorship deals worth tens of millions of pounds, including a four-year agreement with sportswear manufacturer Under Armour and endorsements with Standard Life and Rado Watches.

However, he is known to be careful with his winnings, and returned a £200,000 Ferrari within a year after saying he "felt like an idiot" driving such a flashy car.

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Eagle-eyed photographers also spotted that the luxury watch he donned shortly before lifting the Wimbledon trophy in 2013 displayed the wrong time, indicating that it was worn for publicity purposes and wasn't his day-to-day choice of timepiece.