Afghans refugees living in Iran are being plunged deeper into poverty as sanctions slapped on Tehran over its disputed nuclear drive sap the economy, a refugee agency has warned.

"Sanctions on Iran have been bad news for both Afghan refugees and for humanitarian operations," Jan Egeland, secretary general of the Norwegian Refugee Council (NRC), told Agence France Presse during a visit to Tehran this week.

Beijing on Monday dismissed as "groundless" allegations that a Canadian naval engineer is a Chinese spy.

Qing Quentin Huang, 53, was charged at the weekend under Canada's Security of Information Act with two counts of attempting to communicate classified information to a foreign entity.

Overnight attacks by Boko Haram Islamists forced authorities on Monday to impose a 24-hour curfew in Maiduguri, northeast Nigeria, closing the airport and shutting roads into and out of the city.

The government in Borno state said the decision was taken after consultation with the military, which is believed to have been the target of the strikes by hundreds of militant fighters.

Suspected rebels in Indian Kashmir shot dead a police officer and wounded two of his colleagues on Monday outside the main city of Srinagar, an official said.

Unknown gunmen opened fire on the officer who was patrolling a market in Chadoora, 25 kilometers (16 miles) from Srinagar, in an attack that also injured a shopkeeper, the police official said.

Singapore, which has Southeast Asia's most modern military, said Monday it was acquiring two new submarines from German defense contractor ThyssenKrupp Marine Systems.

In a statement, the defense ministry said it signed a contract to acquire two "Type 218SG" submarines, which are projected to be delivered in 2020.

Experts carried out DNA tests Monday to identify the 33 people who were on a Mozambique Airlines plane that crashed in Namibia killing all on board, an official said.

Thirty one bodies had by late Sunday been pulled from the charred wreckage of the plane in the swamps of northern Namibia's Bwabwata National Park.

Taiwan said Monday its military planes have made about 30 flights into a part of China's newly declared air defense zone which overlaps a similar Taiwanese zone.

China's unilateral announcement on November 23 of an Air Defense Identification Zone (ADIZ) in the East China Sea has angered the United States, Japan and South Korea as well as Taiwan.

Bangladesh's 18-party opposition coalition confirmed Monday it would boycott a general election scheduled for January just hours before a final deadline for nominations, plunging the volatile country into political uncertainty.

"There is no question of us filing nominations for the January 5 election under the present circumstances. We're not going to take part in the January 5 elections," Shamsher Mobin Chowdhury, a vice president of the Bangladesh Nationalist Party (BNP), told Agence France Presse.

Australia's spy agency offered to share information about its own citizens with foreign intelligence partners, according to leaked documents published Monday, sparking calls for an inquiry.

The latest revelations by U.S. intelligence fugitive Edward Snowden, reported by The Guardian Australia, show that the Defense Signals Directorate (DSD) discussed the option of sharing "medical, legal or religious information".

A suicide attacker rammed an explosives-laden truck into a police base near Kabul on Monday, killing four officers and wounding 17 other people including a local police chief, Afghan officials said.

The Taliban, the main Islamist militant group behind Afghanistan's 12-year insurgency, claimed responsibility for the attack in the Nerkh district of Wardak province, southwest of the Afghan capital.