By Jonathan Davies

Volkswagen has officially become the world's biggest car company, overtaking Toyota in terms of sales for the first time.

The German car manufacturer sold 5.04 million vehicles in the first half of the year, compared to Toyota's 5.02 million.

Toyota said sales fell 1.5% compared with the same period last year due to slowing growth in emerging economies.

Volkswagen had aimed to become the world's biggest car company by 2018.

The manufacturer has been boosted by huge growth in China, which now accounts for a third of its total car sales. But Stefan Bratzel, head of Germany's Center of Automotive Management, warned that it will need to withstand slowing growth in China to retain top spot.

He said: "VW is snatching the sales crown in difficult times with major car markets in decline. They will need to withstand the slowdown in China if they want to keep the top spot."

Volkswagen, which also owns Audi and Porsche, is hoping to sell "moderately" more than the 10.1 million cars sold in 2014. Toyota last year sold 10.23 million, but expects that number to drop to 10.15 million in 2015.