Suspected Islamic extremists have kidnapped an elderly missionary couple in northern Burkina Faso.

Ken and Jocelyn Elliott, who are Australian and in their 80s, were abducted on the same day as al-Qaeda launched a deadly attack on a hotel in the country's capital, Ouagadougou. It is unclear if the attacks were related.

Although the couple's whereabouts are unknown and no reason has been given for the kidnapping, a militant group in nearby Mali told Australian media the al-Qaeda-linked Emirate of the Sahara group was holding the couple.

Dr Elliott and his wife Jocelyn have lived in Djibo, near the Malian border, since the 1970s and have built up a 120-bed hospital where Elliott is the only surgeon.

"Our ultimate aim is to show the love of God and the goodness and power of Him through medicine," said Elliott on a previous occasion.

Locals in Djibo have started a social media campaign calling for their release.  The "Djibo supports Dr Ken Elliott" Facebook page has several thousand likes with many messages of support being posted from around the world.

Elliott's hospital is the only one for hundreds of kilometres and the Facebook page pleads for his return, saying his "numerous patients are waiting for him".

"Elliott is all for us and we need him like a baby needs his mother," said resident Moussa Dicko, quoted on the page.

"Elliott is a Burkinabe and a humane person," said Francois Ramde. "He represents the best of humanity."

"Let the name of God not be used in connection with this ignoble act because it was God who sent Elliott to us and will bring him back," said Roots Hassane.

Although no group has claimed responsibility for the abduction, a BBC West Africa correspondent, Thomas Fessy, said the "kidnapping bears the signs of an operation mounted by al-Qaeda in the Islamic Maghreb (AQIM)".

The same group claimed responsibility for the attacks in Ouagadougou last Friday where 28 people were killed and a further 56 injured.

Experts suggest the Elliots may have been taken across the border into Mali, and diplomats are expecting a ransom request to be made.