MORE than 50 people have been killed in the Kenyan coastal town of Mpeketoni, after several attacks by armed militants.

The Somalia-based Islamist group al-Shabab has claimed responsibility for the massacre, which it said was carried out in retaliation after Kenyan troops entered Somalia in 2011 to combat the militants.

On Sunday, about 20 men entered Mpeketoni and went door to door, shooting any non-Muslim men they found. Some of the victims were watching the World Cup in a cinema, or were dragged from a hotel. A police station was also raided by the militants, who arrived in two minibuses.

Witnesses described seeing gunmen demand that locals recite verses from the Qur'an to prove that they were Muslims. If they were unable to do so, they were immediately shot with assault rifles.

Mpeketoni is a short distance from the popular tourist resort of Lamu Island. An al-Shabab spokesman said on Monday: "To the tourists visiting Kenya, we say this: Kenya is now officially a war zone, and as such any tourists visiting the country do so at their own peril."

The spokesman said the attack was revenge for the Kenyan government's "brutal oppression of Muslims in Kenya through coercion, intimidation, and extrajudicial killings of Muslim scholars", as well as operations in Somalia.

A second attack took place overnight on Monday, in two villages close to Mpeketoni. It is reported that 15 people were killed, and a further 12 women kidnapped by the Islamists. Al-Shabab has claimed responsibility.

The President of Kenya, Uhuru Kenyatta, however, has claimed that the violence was not planned by al-Shabab, but was instead caused by ethnic fighting and "local political networks".

The coastal area around Mpeketoni has experienced tribal conflict before, between the Kikuyus, who are predominantly Christian, and other mainly Muslim communal groups, such as ethnic Somalis, or the Oromos. Some opposition politicians have dismissed the President's claims, and witnesses reported hearing the militants speak Somali.

President Kenyatta has been charged with crimes against humanity by the International Criminal Court, after the ethnic violence that followed the disputed 2007 presidential election, in which about 1300 Kenyans were killed.