This is the BBC news. Hello, I am Nick Kelly.

President Barack Obama has made a scathing attack on the Republican candidate Donald Trump saying he is unfit to serve as president. He also questions why the Republican Party is continuing to support Mr. Trump's candidacy. AnthonyZarker reports from Washington. “The president took the opportunity to offer this slashing criticism as Mr. Trump is embroiled in an ongoing feud with the parents of a Muslim American soldier killed in the Iraq war. The real target of Mr. Obama's comments, however, maybe the leaders of the Republican Party who condemn their nominees recent controversies in one breath, but stand by their endorsements of human the next. There has to come a point at which you say enough, the president said. That hasn't happened yet, but with each new Trump related political fire storm, Mr. Obama is more than happy to make them feel the heat.” Mr. Trump hit back accusing Mr. Obama a failed leadership. The head of the Democratic National Committee in the United States has resigned. Amy Dessy's decision to step down comes in the wake of thousands of leaked emails suggesting the Democratic Party's establishments deliberately undermine the campaign of Hillary Clinton's former rival Bernie Sanders for the presidential nomination.

A car bomb in the Libyan city of Benghazi has killed at least 18 people and wounded many others. The bombing comes a day after the first US air strikes in support of the Libyan government’s offensive against Shura, a strong hold of the Islamic State group. Rana Jawad is in Tripoli. “The bombing targeted the headquarters of the 146th brigade, a security force that has been engaged in fighting against Islamist Militias in the city. Dozens were killed and injured. The blast was near a petrol station and a residential district of Benghazi. There was recently the scene of heavy fighting. The Benghazi Revolutionary Shura Council, also known as the BRSC, has reportedly claimed responsibility for the deadly attack.”

The United Nations has warned of a looming humanitarian catastrophe in South Sudan whereas tens of thousands of people flee renewed violence, armed groups have stocked many from reaching neighboring Uganda. Imogen Fox has the details.“The UN described South Sudan as a massive humanitarian crisis with 1.6 million people now displaced. For those fleeing and for those who stay, violence is not the only risk. There is a cholera outbreak and severe food shortages. Children are especially vulnerable, thousands of refugees, many of them malnourished children, have arrived South Sudan's border with Uganda. The UN is gearing up to support them, but warns the sheer number of people fleeing may outpace the capacity of aid agencies to help them.” A peace deal between the government and Reyek Machar broke down last month. World news from the BBC.

Intense fighting has been continuing around the Syrian city of Aleppo where a rebel offensive is trying to break the government siege of opposition held areas. The latest assault began with the explode of huge tunnel bomb underneath Syrian army positions southwest Aleppo.

The security forces in Colombia say they have destroyed more than 100 Cocaine laboratories in a five-day campaign. Official said the operation was part of a new strategy to target producers and traffickers of Cocaine rather than the poor farmers who grow the Coca plant.

After numerous technical problems and a huge cost overrun, the United States air force says the first scourge of its newest stealth flight, Fighter the F35is combat-ready. Almost 2500 planes plan to equip the air force, navy and marines, Nearly 400 billion dollars, is the Pentagon's most costly project ever.

Ireland’s second most senior Roman Catholic leader, the archbishop of Dublin,says he would no longer send Trainee priests from his archdiocese to study at the national seminary after a long mis-allegations of gay culture there. Our Ireland correspondent

Chris Page reports. “Archbishop Diarmuid Martin said accusations were being made anonymously through letters and blogs. The President of Saint Patrick's college Monk senior Hill Cornally acknowledged that the anonymous corresponds was difficult, but he said the college had no concrete details of sexual misconduct. All trainee priests at Maynooth are expected to live in celibacy and preparation for life in the priesthood. Mt. Senior Cornally said that principle was nonnegotiable, but the college authorities could not act unless they had clarity.”

An Egyptian-born American Nobel winning scientist Ahmed Zewail has died in the United States where he worked for the past 40 years, he was 70. AhmedZewail won the Nobel Chemistry prize in 1999. He was the first Arab scientist to win a Nobel Prize. BBC news.