Kenya On lockdown as Obama comes to talk security, trade

US President Barack Obama arrives in his ancestral homeland Kenya late Friday, with a massive security operation under way to protect him from Al-Qaeda-linked Somali militants.

Obama, making his first visit as president to his father's birthplace, will address an entrepreneurship summit and hold talks on trade and investment, security and counter-terrorism, and democracy and human rights.

Parts of the Kenyan capital Nairobi have been locked down and airspace will be closed during the president's arrival late Friday and his departure late Sunday, when he travels up the Rift Valley to neighbouring Ethiopia, the seat of the African Union.

At least 10,000 police officers, roughly a quarter of the entire national force, have been deployed to the capital.

Top of the list of security concerns is Somalia's Shebab militants, who have staged a string of suicide attacks, massacres and bombings on Kenyan soil, including the bloody attack on the Westgate shopping mall in the heart of the capital nearly two years ago that left 67 dead.