Allegations of summary executions, aerial bombardments of civilians and enforced disappearances in Sudan's South Kordofan could constitute crimes against humanity or war crimes, the U.N. said Monday.

"If substantiated (the allegations) could amount to crimes against humanity, or war crimes for which individual criminal responsibility may be sought," according to the preliminary results of a U.N. investigation into a series of incidents in South Kordofan between June 5 and 30.

A policeman and four Taliban insurgents were killed overnight when militants attacked government offices in central Afghanistan, the local police chief said Monday.

The attack in the Qarabagh district of Ghazni province lasted about an hour and started when the Taliban launched two rockets at the district's administrative headquarters before opening fire on a police checkpoint nearby.

British Prime Minister David Cameron announced Monday a sweeping review of government policy to reverse a "slow-motion moral collapse" that he blames for last week's riots that left five people dead.

He also pledged an "all-out war" on street gangs as Britain struggles to find answers to its worst civil disorder for decades, which tarnished the country's image abroad just a year before London hosts the 2012 Olympic Games.

Turkey has denied the capture of a senior leader of the outlawed Kurdistan Workers' Party (PKK), after media reports quoting Iranian officials sparked confusion.

"There has been no confirmed news or development at the moment. We'll make it public if any development takes place," Foreign Minister Ahmet Davutoglu was quoted as saying in the Turkish media late Sunday.

Russian security services have foiled a plot by a group of Islamists to blow up a high-speed train running between Moscow and Saint Petersburg, the Kommersant business daily said Monday.

A blast on the same route that authorities blamed on Muslim rebels killed 26 people in November 2009.

Iranian President Mahmoud Ahmadinejad called nuclear weapons a waste of money Sunday as he prepared to receive a top Russian security official for crisis mediation talks.

Ahmadinejad said he was looking to build a closer relationship with Moscow and expecting to see the Russian-built Bushehr nuclear power plant -- Iran's first -- start producing electricity next year, after many delays.

Iran's first nuclear power plant, built by Russia, will be connected to the national grid in late August, atomic chief Fereydoon Abbasi Davani told the Arabic-language network Al-Alam on Sunday.

"The test to reach 40 percent of the plant's power capacity has been done successfully ... God willing, we will be able to commission the plant by the end of Ramadan with an initial production" of the same amount, Abbasi Davani said.

British Prime Minister David Cameron pledged a "zero tolerance" crackdown on gangs after recent riots, despite a deepening row with police chiefs over plans for a U.S. "supercop" to advise the government.

Top British police officers criticized Cameron's move to hire ex-New York police chief Bill Bratton to help prevent a repeat of the violence in which five people died, saying a homegrown model of policing was needed instead.

Anders Behring Breivik, who last month carried out the most murderous attacks on Norwegian soil since World War II, has returned to the site of his island massacre to describe the killing, police said Sunday.

The 32-year-old rightwing extremist who on July 22 first set off a bomb outside government offices in Oslo then went on a shooting rampage on the nearby island of Utoeya, killing 77 people in all, was "interrogated by police on Utoeya" Saturday, Oslo police said in a statement without providing any further details.

Pakistani police scrambled for leads Sunday on an American aid expert kidnapped at gunpoint from his house in Lahore, interrogating his guards and combing their phone records for clues.

The U.S. embassy named the man as Warren Weinstein, who Pakistani police said was the country director for U.S.-based consultancy J.E. Austin, which works on development projects in the frontline state in the war on al-Qaida.