BBC News with Jonathan Wheatley

The main contingent of an Arab League observer (mission) has arrived in Syria to monitor an initiative to end the continued violence. It has left thousands dead since anti-government protests began earlier this year. At least 18 people are reported to have been killed in the latest (shelling) of the city of Homs. The Arab League initiative agreed with the Syrian government requires all armed forces to withdraw from the areas of conflict. The BBC's Jim Muir in Beirut says it's not clear whether the observers' (movements) will be restricted.

Syrian officials are saying they are committed to the protocol they signed with the Arab League that the observers will have complete freedom of movement, but of course they do have to coordinate with the Syrian authorities because they need to have security; they can't just jump in cars and drive off to a place like Homs. So that in a sense makes them sort of dependent on the regime.

Hundreds of ultra-Orthodox Jews have (clashed) with police near Jerusalem as tensions mount over their campaign of segregation between men and women. A police officer was wounded in the town of Beit Shemesh as police were called to (remove) a sign on a main road ordering segregation between the sexes. Here's Aidan Lewis.

Ultra-Orthodox Jews pelted police and journalists with rocks and eggs, and (set fire to) rubbish bins. They also re-installed a number of placards ordering segregation that had earlier been removed. Beit Shemesh has become a focus of friction between ultra-Orthodox and more secular-minded Jews. Prime Minister Benjamin Netanyahu says police will continue to arrest ultra-Orthodox offenders and insists that there's no place in Israel for discrimination.

The authorities in Mexico say they've arrested the chief bodyguard of the country's most wanted drugs baron, the fugitive Sinaloa cartel boss Joaquin "El Chapo" Guzman. The bodyguard, Felipe Cabrera Sarabia, was detained by army special forces. Colonel Ricardo Trevilla of the Mexican army said Cabrera had risen through the ranks of the cartel.

"Cabrera used violence to keep control of the group's criminal activities. This allowed him to gain stature in the group. It allowed him to become a key player in drug smuggling and trafficking. It helped him become a security provider for the head of the cartel in his area of operations."

The head of the army in Guinea-Bissau, General Antonio Inaja, has said an attack on the general staff headquarters and other military bases in the capital has been foiled. He said the army and the government remained in control of the country following an attempt to seize (weapons) from military armories.

Hundreds of people have attended a memorial service in Nigeria at the Roman Catholic Church where more than 30 people were killed in a bomb attack on Sunday. The blast on the outskirts of the capital Abuja was the first in a series of attacks on Christmas Day.