Image copyright AP Image caption Warren Buffett, nick-named 'the Sage of Omaha' is known for taking the long view on his stock market investments

Billionaire investor Warren Buffett has described his decision to invest in Tesco as a "huge mistake".

Mr Buffett's Berkshire Hathaway firm owns a 3.7% stake in Tesco, worth hundreds of millions of dollars.

But the supermarket's share price has fallen to an 11-year low this year on the back of declining sales and an investigation into its accounts.

"I made a mistake on Tesco. That was a huge mistake by me," the legendary investor told CNBC.

Mr Buffett is known for taking long-term bets on established companies rather than investing in riskier stocks.

His portfolio of investments include well-known names like Coca-Cola, IBM and American Express.

Berkshire Hathaway began building a stake in Tesco in 2006, and by 2012 owned more than 5% of the business.

By the end of 2013 the stake had fallen to 3.7%, but still represented an investment of nearly $1.7bn.

But since then Tesco's share price has fallen nearly 50%, cutting the paper value of the investment in half.

Tesco has seen declining sales amid increased competition from discount retailers like Aldi and Lidl, and growth of high-end offerings from Marks & Spencer and Waitrose.

It has issued a string of profit warnings, and shocked investors last week when it revealed it had overstated its expected half-year profits by £250m.

The Financial Conduct Authority has confirmed it is investigating the issue, following the launch of an internal investigation and the suspension of senior members of staff.