Technology firm Yahoo has appointed leading Google executive Marissa Mayer as its next chief executive, BBC News reported.


Mayer, 37, will become the firm's third CEO in the space of a year.


In a statement released by Yahoo, Mayer said she was "honoured and delighted" to lead the company.


In May CEO Scott Thompson stepped down after accusations that he put a fake computer degree on his CV. In September 2011, CEO Carol Bartz was fired after two-and-a-half years in the post.


Yahoo has struggled in the face of increased competition from search rivals including Google and the emergence of social giants such as
Facebook.


Although it remains the US' largest web portal, correspondents have said Yahoo's failure to become more "social" has hurt the firm.


Yahoo's news service is said to still attract very large volumes of traffic. But other products, such as its search engine and email, have suffered. The company's revenue from display advertising has also dwindled.