“It is not possible that someone can come from a neighbouring country and go straight to a particular house and take away someone,” police chief Mathew Iteere told reporters.
“It is not possible at all and that is why we strongly believe that they (abductors) have got sympathisers or cells or what we refer to as sleepers within the region.
“And those are the people we are targeting and we have already several arrests … but we believe the larger group is from across (the border),” Iteere added.
An armed gang seized Marie Dedieu, 66, early on Saturday from Manda Island in the Lamu archipelago, and fled by sea. It was the second kidnapping of a foreigner from the area in less than a month.
Dedieu and her partner had only returned from a trip to France earlier the same week, a factor that led authorities to conclude the attackers may have been tipped off.
A police official who did not want to be named said seven suspects were being held for questioning.
“Those in custody include a security guard who worked within the area where the woman was kidnapped,” said the official.
“Investigators are interrogating them to establish if they know how the abduction occurred or have any link with the abductors because the foreign gang must have been working with some locals in the region.”
The Kenyan police chief said they were working to free Dedieu and British tourist Judith Tebbutt who was seized on September 11th north of Lamu and also taken to Somalia.
“There is a lot that is happening in a bid to ensure we get the kidnapped women back safely but we don’t want to keep on talking about the nitty gritty because these are issues that can easily jeopardise the investigations.”