It may be Nokia World, but WhatsApp CEO Jan Koum just used the Nokia event in Abu Dhabi to announce that his mobile messaging startup has now hit 350 million monthly active users — that’s up 50 million in just two months.

Koum, who is known for being somewhat elusive with press, made the reveal while talking about WhatsApp’s ongoing partnership with Nokia — which now includes photo sharing directly from the camera of the three new Asha devices that Nokia unveiled today.

BXKcuWjCUAAitd  Mobile messaging service WhatsApp now has 350 million active users each month

Nokia is clearly a key partner for WhatsApp, and that’s evidenced by Koum’s admission that the messaging service receives some 250,000 new sign-ups from all Nokia devices — including Symbian, Asha and Lumia phones — every single day.

Today’s news signals more impressive growth for WhatsApp — which hit 300 million monthly active users in August, when it was processing 31 billion messages per day: 11 billion messages sent and and 20 billion messages received.

Images via abulhussain / Flickr and @poderpda