Taiwan's coastguard said Friday it would stage a live-fire exercise next month in disputed South China Sea islands, a move that could raise regional tensions.

The drill will take place on Taiping Island between April 9 and 11 in the Spratlys, a sprawling group of islands claimed in whole or part by Taiwan, China, Vietnam, Malaysia, the Philippines, and Brunei.

Among other weaponry, the drill will involve 40mm artillery and 120mm mortars, both shipped to the island last year to boost Taiwan's defence capability in the Spratlys, according to the coastguard.

Taiping is the biggest island in the Spratlys and has long been governed by Taiwan, which maintains a small coastguard garrison there.

Vietnam voiced anger after Taiwan moved the new, longer-range artillery and mortars to Taiping Island last year.

All claimants except Brunei have troops based on the archipelago of more than 100 islets, reefs and atolls, which cover a vast area but have a total land mass of less than five square kilometres (two square miles).

The potentially resource-rich sea, home to important trade routes, is a potential military flashpoint and there has been a string of diplomatic rows between countries with overlapping territorial claims in recent years.

The Philippines and Vietnam have complained that China is becoming increasingly aggressive in its actions in the area -- such as harassing fishermen -- and also through bullying diplomatic tactics.

Taiwan ex-lieutenant jailed for leaking secrets to China
Taipei (AFP) March 1, 2013 - A former navy lieutenant was sentenced to three years in prison for leaking confidential military information to China, a court said Friday.

Chien Ching-kuo, discharged from the navy in 2009, was convicted of leaking national secrets to a Chinese agent in 2011 in return for unspecified favours he received in China, the High Court said in a statement.

Chien collected confidential information, including some of Taiwan's warship deployments and missions, through his former comrades in the navy and passed on the intelligence to China in 2011, according to the statement.

The court said it showed leniency for Chien in its sentencing as he has collaborated with the authorities and shown remorse for his act. He can appeal the ruling.

Chien and two former comrades, including an ex-chief officer in charge of political warfare at the naval meteorology and oceanography office, were arrested last year on suspicion on leaking secrets to China.

The office keeps classified information such as mapping and charting publications of the meteorological and oceanographic battle environment, military experts say.

Military prosecutors are investigating charges against the two other men as they were on active duty at the time of the alleged crime.

In a separate case a retired Taiwanese lieutenant general was Thursday charged with spying for China after allegedly collecting intelligence on Taiwan's military and political situation and handing his findings to Beijing, prosecutors said.

Taiwan and China have spied on each other ever since they split in 1949 at the end of a civil war. Beijing still regards the island as part of its territory awaiting reunification, by force if necessary.

Taiwan has been hit by a string of spy scandals in recent years, reflecting the fact that intelligence gathering has continued despite warming ties with China under the island's current Beijing-friendly government.