Nelson Mandela is "much better" and responding satisfactorily to treatment after a week in hospital suffering from pneumonia, the South African presidency said Wednesday.

The frail 94-year-old anti-apartheid hero is steadily improving and doctors are happy with his progress, President Jacob Zuma's office said in a statement.

The discovery of an unexploded World War II bomb unearthed near Berlin's main train station snarled rail and road traffic in the German capital Wednesday, authorities said.

"The bomb was found yesterday (Tuesday) afternoon on property belonging to the rail company," a police spokesman told AFP, adding that sappers planned to defuse it Wednesday.

There is no consensus on an international arms trade treaty, major weapons exporter China said Wednesday, after it abstained as the U.N. General Assembly passed the measure by 154 votes to three.

The only votes against the first treaty on the conventional arms trade were from Syria, North Korea and Iran.

A Thai marine has been abducted and killed in Thailand's deep south in a revenge attack by militants who carried out a botched raid on a military base, police said Wednesday.

Maela Tolu, a 24-year-old Muslim private at the base, was snatched from his home by eight gunmen on Monday evening, his wife told police in Narathiwat, one of several insurgency-plagued provinces near the Malaysian border.

Four sisters in north India have suffered burn injuries after two men threw acid on them as they were returning from school, police said on Wednesday, with one victim admitted to hospital.

The incident took place in the Shamli district of Uttar Pradesh, about 100 kilometers (60 miles) from the capital, on Tuesday evening when the sisters, three of whom are teachers, were returning home from a government school.

At least eight people died after torrential rain and strong winds battered Buenos Aires and its suburbs, knocking out power, downing trees and affecting 350,000 residents, officials said Tuesday.

More than six inches (155 mm) of rain fell between midnight Monday and 7 am Tuesday, the city weather service said, setting an April record for the Argentine capital.

Serbia and Kosovo failed Wednesday to find common ground on how to defuse longstanding tensions at EU-sponsored talks, officials said.

"The gap between the two sides is very narrow but deep," said EU foreign affairs head Catherine Ashton, who chaired the eighth round of talks in Brussels aimed at normalizing ties between Serbia and breakaway territory Kosovo.

North Korea blocked access to a key joint industrial zone with South Korea on Wednesday -- a sharp escalation in a military crisis that Washington blamed on Pyongyang's "reckless" behavior.

North Korea informed Seoul in the morning that it was stopping the daily movement of South Koreans into the Seoul-funded Kaesong complex -- 10 kilometers (six miles) inside the North side of the border.

Pope Francis on Tuesday visited the tomb of John Paul II at St Peter's Basilica, exactly eight years after the former pope's death, the Vatican said.

"(...) The pope kneeled for a long time praying in front of Blessed John Paul II in the Chapel of St. Sebastian," it said in a statement, adding he also made brief stops in front of the tombs of John XXII and St. Pius X.

Venezuela's presidential campaign to replace Hugo Chavez formally kicked off on Tuesday, with his chosen successor, acting President Nicolas Maduro, vowing to honor his socialist legacy at the late leader's childhood home.

As Maduro visited Chavez's hometown of Sabaneta in the west, opposition leader Henrique Capriles was heading to the opposite side of the country in the eastern state of Monagas for the short campaign ahead of the April 14 vote.