SAN FRANCISCO (REUTERS) - Apple Inc's quarterly revenue and earnings beat Wall Street's targets on surprisingly strong sales of its flagship iPhone, sending its shares up 4 per cent.

But profit slid 22 per cent in its fiscal third quarter as margins were pressured by growing competition and a wider array of lower-end devices such as older smartphones.

Apple earned US$6.9 billion (S$8.7 billion), or US$7.47 a share, on revenue of US$35.3 billion. That compared with a profit of US$8.8 billion, or US$9.32 a share, on revenue of about US$35 billion in the year-ago quarter.

Wall Street's average forecast was for revenue of US$35.02 billion and earnings per share of US$7.32, according to Thomson Reuters I/B/E/S.