Packing winds of 185 kph (114 mph) near the centre and gusts of up to 220 kph, Typhoon Usagi weakened after hitting the Batanes island group, and is moving slowly west-northwest at 19 kph towards southern China, the weather bureau said.

Usagi, which has been labelled a super typhoon, made landfall on Itbayat, the Philippine island closest to Taiwan, toppling communication and power lines, uprooting trees, causing landslides and flooding rice and garlic farms.

"It's rare that we suffer casualties as a result of typhoons," Budget Secretary Florencio Abad, a former congressman for Batanes, told Reuters, saying the province had not experienced a powerful typhoon in 25 years.

"A flash flood occurred and trees were uprooted from the mountain and swept by roiling waters to the town. Many houses lost their roofs or were destroyed. Damage to crops is heavy and landslides were reported all around."