BBC News with Jonathan Izard.

The head of the Ukrainian navy Denys Berezovsky has been removed from his post after he pledged allegiance to the new pro-Russsian authorities in Crimea. Kiev has put him under investigation for treason. Admiral Berezovsky made his announcement in a room full of armed Russian soldiers.

“I, Berezovsky.. pledged allegiance to the residents of the autonomous Republic of Crimea and the heroic city of Sevastopol. I vowed to strictly follow orders from the commander in chief of the autonomous Republic of Crimea as well as orders by military commanders appointed by them, and to abide by the military code of practice.”

The BBC's Mark Lowen is in the Crimean port of Sevasopol, a major base of Russia's Black Sea naval fleet.

Extraordinary developments tonight with the defection of the head of the Ukrainian navy Denys Berezovsky Rear Admiral, who's now sworn allegiance to the prime minister of Crimea, newly-appointed pro-Russian prime minister of Crimea, so in effect, Kiev has lost control of its most senior naval official and that is a huge challenge to Kiev. And yes another sign that actually Crimea is slipping out of the control of the Ukrainian government.

In a phone call with the German Chancellor Angela Merkel, the Russian President Vladimir Putin described the measures taken by Moscow as fully appropriate. A German government spokesman said Mr. Putin had agreed to establish a fact-finding mission and a contact group to start political dialogue between Russia and Ukraine whose new administration Moscow refuses to recognize. Nato's General Secretary Anders Rogh Rasmussen has called for the deployment of international observers to Ukraine to defuse tension there. He was speaking after an emergency meeting of Nato ambassadors in Brussels.

“We urge both parties to immediately seek a peaceful resolution through dialogue, through the dispatch of international observers under the auspices of the United Nations Security Council or the OECE.”

The US Secretary of State John Kerry has described Russia's military operation in Ukraine as an incredible act of aggression. He spoke of possible visa bans, asset freezes and trade isolation in response.

Hundreds of thousands of Ultra-orthodox Jews have protested in Israel against government plans to draft them into the army. They traveled from across the country to hold a prayer vigil in Jerusalem, carrying banners with slogans such as “we will not join the military”. Women and children also took part. Secular Jews are required to serve in Israel, but traditionally, Ultra-orthodox Jews have claimed exemption on religious grounds. These protesters explained their objections to the government's plans.

“The lifestyle is waking up in the morning, going to Synagogue and learning, that's all it is, there's nothing pass there, and doing this, going to the army is not gonna be the right thing at all.”

“About..that you know, our service is to god and we split up into two sections. If you fit enough to go to the army, if you fit to serve god and to help the army, that way, that's we are doing.”

World News from the BBC.

A shaky truce in the besieged Palestinian refugee camp in Yarmouk on the outskirts of Damascus has broken down after the warring sides exchanged shelling and gunfire. The truce was reached in mid-February by Islamist rebels and Palestinian militants loyal to President Bashar al-Assad. A UN spokesman said the fighting had disrupted its recent relief operation to 40,000 Palestinians who've been under siege since last summer.

Thailand's army chief has ordered action against groups advocating a separate state in the north of the country. A number of organizations that support the Prime Minister Yingluck Shinawatra are calling for an independent state there in response to months of anti-government protests in Bangkok. Jonathan Head reports.

Hardly a day passes now without a dramatic statement from General Prayuth Chan-ocha, the powerful commander of the Thai army. General Prayuth has asked his regional commander to take action against the group which has begun promoting the idea of a Lan Na People' Democratic Republic. Lan Na was the name of the old kingdom in the north before is was absolved into Thailand just over a century ago. He did not specify what action he had in mind. But his comments suggest the military is taking the threat of separatism seriously.

The United Nations Humanitarian Co-ordinator in the Central Africa Republic has warned of an impending food crisis there after almost a year of communal and inter-religious violence. He said humanitarian problems were deepening. And unless action was taken, people would soon die of hunger. He said many people were too afraid to return home.

The government of Italy has called for an emergency meeting to discuss how to save the ancient city of Pompeii from further ruin, following fresh collapses this weekend. The culture minister asked officials to explain why a wall of the tomb and part of an arch of the Temple of Venus had fallen down after days of heavy rain. A series of problems in the Roman city four years ago sparked an international outcry over the neglect to one of the world's most treasured archeological sites. Pompeii is one of Italy's most popular attractions.

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