Some 11 Kenyan lawmakers have been questioned by police after visiting neigbouring Somalia at the weekend.

They met Somali President Mohamed Abdullahi Farmajo to talk about how to deal with the militant Islamist group al-Shabab, according to Kenyan TV station NTV.

But the trip was not officially approved, security secretary Muriithi Kangi is quoted as saying by the privately-owned Daily Nation newspaper.

Kenya's television station NTV posted on YouTube a video of the lawmakers' arrival at the airport.

The lawmakers argued that they had travelled in their personal capacities.

They were briefly held "for discussions with police" on their return to the capital's main airport, but were released and will not face any charges.

Most of them represent north eastern constituencies that border Somalia where al-Shabab often attack civilians.

Schools in the region have been closed and non-native civil servants have fled following recent attacks.