Twitter Inc reported its slowest growth in quarterly revenue since going public in 2013 as the company faces intensifying competition from fast-growing competitors such as Snapchat and Instagram.

The microblogging service operator's shares plunged 10 per cent in extended trading as revenue for the quarter fell short of analysts' estimates. Revenue forecast for the current quarter also came in below estimates.

Twitter's user base, however, modestly increased to 313 million average monthly active users in the second quarter from 310 million in the first quarter.

The company, which has been struggling with stagnating user growth and lower spending by advertisers, is doubling down on efforts to attract users.

Under co-founder and CEO Jack Dorsey, the company is working to better define its role in the growing social media landscape. Twitter rolled out a video ad this week that showed it as the place to go for live news, updates and discussion about current events.

The company has also pushed further into live video and streaming and has signed deals with Major League Baseball and the NBA to revive user growth.

Twitter forecast current-quarter revenue of $590 million-$610 million, well below the average analyst estimate of $678.18 million.

Excluding items, the company earned 13 cents per share, topping the average analyst estimate of 10 cents.

The company's net loss narrowed to $107.2 million, or 15 cents per share, in the second quarter ended June 30, from $136.7 million, or 21 cents per share, a year earlier.

Revenue rose about 20 per cent to $602 million, missing the estimate of $606.8 million.