It is more than three weeks since 200 girls were abducted from the Nigerian village of Chibok by radical jihadist group Boko Haram, but the fight for their return has been helped with a simple hashtag, #BringBackOurGirls.

The message has gone viral across the social media universe, appearing millions of times on Twitter since the abduction on 14 April, and can still be found leading many trending lists.

According to social media analytics firm Topsy.com, the #bringbackourgirls hashtag has been tweeted 2,890,369 times in past 30 days, as it has attratced unprecedented public attention from around the world.

This includes backing from country heads, politicians and celebrities, with UK Prime Minister David Cameron tweeting his support, with US first lady Michelle Obama also posting a picture of her holding a placard of "#BringBackOurGirls".

She tweeted, "Our prayers are with the missing Nigerian girls and their families. It’s time to #BringBackOurGirls." The tweet has been retweeted thousands of time.

Other celebrities who have pledged their support include Kim Kardashian, Nicki Minaj, Piers Morgan, and Chris Brown.

Hadiza Bala Usman, who has spearheaded the social media campaign, told AFP, "This campaign has really exceeded my expectations."

"We are at a point where Nigerians need to know that they have social media as a tool."

"You can’t suppress us. We have a voice."

According to the most recent reports, the governor of Borno state in Nigeria claimed to have information about the 200 abducted schoolgirls.

France has also offered to host a summit to discuss the issue of Boko Haram as a whole, which could be attended by Nigeria’s neighbours, Cameroon, Niger and Chad, as well as major states such as the US, UK and EU.