LIUKUEI: More than 140,000 troops battled Sunday to reach survivors stranded a week after Typhoon Morakot struck as the United States and China offered helicopters to help in the rescue effort.

As the massive operation to airlift people to safety from the devastated areas in southern and central Taiwan continued, President Ma Ying-jeou issued his second apology in as many days for his government's slow response.

"Sorry we were late," Ma told a community meeting in southern Pingtung county. "Still, we hope to get your life back to normal as soon as possible," he added.

The official death toll stands at 124 but Ma has warned that number could rise to more than 500, with hundreds feared buried beneath the rubble in the village of Hsiaolin alone.

After days of mounting criticism, the president convened his first national security meeting on Friday and replaced Taiwan's head of emergency operations.

Within 24 hours of the meeting, the number of troops deployed in rescue operations had increased to 140,000 from 50,000, the defence ministry said.

Helicopters crisscrossed southern mountainous regions, airlifting survivors to safety as troops below fought through raging rivers with collapsed bridges to reach victims, many of whom have been without food for more than a week.

Meanwhile the United States pledged to send heavy-lift military helicopters to Taiwan to help in relief efforts, the foreign ministry said, in what would mark the first time US troops have been deployed on the island in 30 years.

The ministry did not say when the Sikorsky CH-53Es Super Stallions, the US military's largest and heaviest helicopter, would arrive, but national media said they could be here as early as late Sunday.

It would be the first time US troops have stepped onto Taiwanese soil to deliver humanitarian aid since 1979 when Washington shifted its diplomatic recognition from Taipei to Beijing.

And in a sign of warming relations with China, Beijing offered to provide helicopters, The Taipei-based United Daily News quoted Fan Liqing, spokeswoman for China's Taiwan affairs office, as saying.

The offer would include Russian-made helicopters, currently the world's biggest, which Chinese rescuers used during last year's earthquake in China, the report said.

Typhoon Morakot slammed into Taiwan on August 8, dumping more than three metres (120 inches) of rain that unleashed floods and mudslides which tore through houses and buildings, ripped up roads and smashed bridges.

It was the worst-ever typhoon to strike Taiwan, the president said on Friday, saying the scale of the damage was more severe than a 1959 typhoon that killed 667 people and left around 1,000 missing.