Thousands of Kenyan civil servants, teachers and medics have been warned by their unions to leave troubled northeastern regions hit by a wave of insurgent attacks, reports said Tuesday.

The call follows attacks over the weekend, claimed by Somalia's al-Qaida-affiliated Shebab, in which 28 non-Muslims were executed on a bus near the northeastern town of Mandera.

Kenya said on Sunday its troops had killed  dozens of Shebab Islamists in raids inside Somalia after the execution of 28 non-Muslim people on a Kenyan bus.

There was no independent confirmation of the strikes in response to Saturday's attack by the al-Qaida-linked group near Mandera, a northeastern town near the Kenya-Somali border.

Somalia's Shebab Islamists on Saturday ambushed a bus in Kenya, killing 28 non-Muslim passengers in what they said was a revenge attack for police raids on mosques in the troubled port city of Mombasa.

"I can confirm... that 28 innocent travellers were brutally executed by the Shebab," regional police chief Noah Mwavinda told Agence France Presse.

It is an image famous in a thousand postcards: giraffe, rhino and zebra pacing the savannah with city skyscrapers towering in the background.

But flanked by one of the continents fastest growing cities, Kenya's capital Nairobi, east Africa's oldest national park is under threat.

Four people were stabbed to death in Kenya's volatile port city of Mombasa following security raids on mosques in which a man was killed and over 200 people arrested, police said Tuesday.

The gang took to the streets Monday night in apparent revenge attacks, beating some and stabbing others, following the raids earlier in the day targeting the two mosques accused of links with Somalia's Al-Qaeda affiliated Shebab militants.

Hundreds of Kenyans marched through the streets of Nairobi on Monday to protest at the stripping of a woman wearing a miniskirt, saying they had the right to wear what they want.

Protesters turned out to show their outrage following the widespread circulation on social media of a video showing a woman being attacked and stripped by a mob last week in central Nairobi after they said her skirt was too tight and short.

One man was killed Monday as Kenyan security forces arrested over 200 people and seized weapons in raids on mosques accused of links with Somalia's Al-Qaeda affiliated Shebab militants, police said.

Security forces began the operation in the early hours of Monday morning, targeting the Masjid Musa and Sakina mosques in the port city of Mombasa.

Food rations vital for half a million refugees in Kenya will be slashed in half due to an aid shortfall, the United Nations said Friday in an appeal to donors.

"Cutting rations is the last resort," U.N. World Food Program (WFP) deputy chief for Kenya Paul Turnbull said, calling for $38 million more in cash, including an immediate $15.5 million to feed refugees until January.

Kenyan police said Wednesday they had arrested 10 suspected attackers, including two female suicide bombers, who had crossed into the country from war-torn Somalia.

"These 10 suspects were involved in recent terror attacks in Nairobi before they fled to Somalia, and now they have sneaked back," police spokeswoman Gatiria Mboroki told reporters.

Direct talks between South Sudan's president and the country's rebel chief have failed to strike a peace deal, mediators said Friday, but added that discussions would continue over the weekend.

President Salva Kiir and ousted vice president Riek Machar have held two days of meetings in Addis Ababa, with Ethiopian Prime Minister Hailemariam Desalgen and Kenyan President Uhuru Kenyatta leading the latest push for an end to the nearly 11-month-old civil war.