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Syrian opposition groups have called on President Assad to resign immediately and make way for a transition to democracy. It comes as Syrian troops and tanks continue operations in the town of Rastan, where more than 50 people are reported to have been killed. Jim Muir reports from Beirut.

Al-Rastan has been cut off and under attack by troops and tanks for several days now. Conditions for civilians trapped there are reported to be dire. Activists said the town has been under heavy bombardment from artillery and tanks, with some houses being brought down on the heads of families. A four-year-old girl is reported to be among the many who've died. The authorities say they are pursuing "armed terrorist gangs", and there are some independent reports that armed resistance is being met. All of this is going on despite the conciliatory gestures being made by the regime. It's released hundreds of detainees after an amnesty was announced, though thousands more remain.

There's been a series of bomb explosions in the city of Ramadi in western Iraq, killing at least five people and injuring several more. One report said two roadside bombs went off in the main market near the provincial governor's compound and that the blasts were followed by a car bomb.

Thousands of armed men from one of Yemen's most powerful tribes are reported to be clashing with government troops in the north of the capital Sanaa. Dozens of people are thought to have been killed. From our Middle East desk, here's Sebastian Usher.

For now, at least it seems as if the president has seen off this latest challenge. His elite forces appeared to have been used successfully to hold government positions, but the fighting has continued inside Sanaa, with mortar fire and rockets scarring the centre and driving residents to flee. Many people believe the president sees violence and chaos as his best chance of staying in power. He has decades of experience of surviving and even benefiting from various armed conflicts in Yemen, but he's never seemed under siege in quite the same way as fighters bent on his removal approach the very heart of his power.

An American couple who kidnapped a school girl and held her captive for nearly two decades has been sentenced to life in prison. Jaycee Dugard was abducted by Phillip and Nancy Garrido, and held in a compound at the bottom of their garden. From California, Alastair Leithead has this report.

At first, the Garridos denied all charges, but in April changed their plea to guilty. Nancy Garrido was sentenced first - 36 years to life for two charges of kidnap and rape. Phillip Garrido, who had previously been convicted of rape, was given the maximum possible sentence of 431 years for kidnap and 13 charges, including sexual assault, six of them rape. The judge called their treatment of her evil and reprehensible.

World News from the BBC

The World Health Organisation says the deadly food poisoning outbreak in Germany is being caused by a highly-toxic strain of E.coli that's never been detected before. Scientists are still searching for the source of the outbreak, which has killed nearly 20 people and made more than 1,600 ill across 10 European countries.

The former governor of Massachusetts, Mitt Romney, has entered the race to be the Republican candidate to challenge Barack Obama in next year's US presidential election. It's the second time Mr Romney has sought his party's nomination in the race for the White House. In 2008, he was defeated by John McCain. Reporting from Washington, here's Steve Kingstone.

Mitt Romney announced his candidacy during a visit to a farm in the electorally crucial state of New Hampshire, which will host one of the first Republican primaries. His focus was the economy. He said America was in crisis and that Barack Obama had failed the country. Mr Romney said it broke his heart to see fellow citizens out of work, losing their homes and struggling to pay for food and petrol. He portrayed himself as a chief executive for the nation. In early polling, Mitt Romney leads the other declared candidates for the Republican nomination.

A court in Argentina has ruled that the heirs to the country's main media group must submit to DNA testing to clarify whether they were born to left-wing prisoners killed by the armed forces in the 1970s. Judges ruled that Marcela and Felipe Noble Herrera, the adopted children of the owner of the Clarin Group, must give direct DNA samples.

Brazil has launched a welfare scheme aimed at lifting millions of people out of extreme poverty. President Dilma Rousseff launched this scheme at the presidential palace in the capital Brasilia. According to official figures, more than 16 million people live in extreme poverty, earning less than $1.5 a day.