By Jonathan Davies

Facebook has beaten its profit expectations for the first quarter despite a 20% fall.

Facebook reported profits of $512 million (£341m) in the first three months of 2015, down 20% from the same period last year. Despite the fall, it beat analyst forecasts. There was positive news in terms of revenue, which grew by 42% to $3.5bn.

The social network giant also said that the number of people using it on mobile devices grew 24% to 1.25 billion.

Facebook chief executive Mark Zuckerburg described the results as a "strong start to the year".

The results come as investors are worried over the company's slowing revenue growth and rising costs. Facebook has been spending much more on research & development, with costs rising from $181m to $566m.