BBC News with David Austin.

President Obama says Russia has put itself on the wrong side of history by violating Ukraine's sovereignty. He told reporters of the White House that the US was looking at a diplomatic and economic measures intended to isolate Russia.

What cannot be done is for Russia with impunity to put its soldiers on the ground and violate basic principles that are recognized around the world. And I think the strong condemnation that it's received from countries around the world indicates the degree which Russia is on the wrong side of history on this.

The US State Department said reports that Russia had given Ukrainian forces in Crimea an ultimatum to surrender or face assault, if true, would signal a dangerous escalation. The Russians said no such demand had been made. Christian Fraser reports from the Crimean port of Sevastopol.

Ultimatums have come and gone here without incident. This time according to the Ukrainian side, a deadline has been set for Tuesday morning. The Russian said there had been no such threat. Utter nonsense was the phrase Moscow used. But no doubt the pressure is building on those who resist in these Ukrainian bases. In Sevastopol, a cargo ship has now been maneuvered into the mouth of the harbor. Beyond it we can see minesweepers patrolling the bay. It underlines the relentless buildup of Russian forces.

Pro-Russian demonstrators have occupied the regional government building in the eastern Ukrainian city of Donetsk. About 300 protesters forced their way in while a crowd waving Russian flags and according to one report, chanting “Putin Come”gathered outside.

At the opening of his trial in Pretoria, the South African athlete Oscar Pistorius has pleaded not guilty to murdering his girlfriend Reeva Steenkamp. Mr. Pistorius says he mistook her for an intruder. A witness told the court that she heard screams and gunshots from the couple's apartment.

The United Nations has proposed a peacekeeping force for the Central African Republic of nearly 12,000 troops and police with a robust mandate to protect civilians. At least 2,000 people have died and more than 700,000 have been displaced since December in communal violence that followed a coup. Here is our UN correspondent, Nick Bryant.

Concerned by how the circle of violence in the Central African Republic could spiral into genocide, the UN has proposed a peacekeeping force for this war-torn country. Right now, thousands of African Union and French troops are in the country,which will soon be bolstered by soldiers from the European Union. But the UN Secretary General Ban Ki-moon would like to see a blue-helmeted peacekeeping force of up to 10,000 soldiers and 18,000 police. It would include troops from the African Union already on the ground. He would like the force to be given a robust mandate and also adequate resources.

Nick Bryant reporting.

This is the World News from the BBC.

The United Nations Secretary General Ban Ki-moon has urged the Venezuelan authorities to listen carefully to the aspirations of the protesters and engage in dialogue with the opposition. He was speaking ahead of a scheduled meeting in Geneva with the Venezuelan Foreign Minister Elias Jaua. Eighteen people have died in nearly a month of anti-government protests in Caracas and other cities.

An Egyptian government minister has told the BBC that it was a mistake for the authorities to put a group of journalists from the broadcaster Al Jazeera on trial charged with aiding the Muslim Brotherhood. The Minister for Investment and Foreign Trade Mounir Fakhry Abdel Nour alleged of the journalists including a former BBC correspondent Peter Greste had been working for a television channel that served the purposes of a terrorist organization. But he said he would react differently to the situation. The journalists denied all the charges against them.

An attack by suspected Islamist militants in northeastern Nigeria has left more than 30 people dead. A senator from Borno state told the BBC that the militant group Boko Haram sent a warning before the raid on the town of Mafa on Sunday night and many people fled to the nearby city of Maiduguri. He said soldiers also fled. Nigeria's Interior Minister Abba Moro says they are doing everything they can to try and stop the violence, but it will take time.

This is a world blamed series of attacks and activities by the Boko Haram, the civilian activity in Nigeria for which these government was not completely prepared to tackle. But at least that this government was accepted by the crowd. Every resource that is valuable to combat our Nigerian rebel.

Nigeria's Interior Minister Abba Moro.

Hundreds of Muslims are being protesting in Mauritania's capital Nouakchott following reports that copies of Koran had been desecrated at a mosque. The Imam said the 4 men entered the mosque, tore apart the books and threw them into a toilet. Police fired teargas to disperse the protesters.

BBC News.