NANNING - Authorities have recently raised the minimum wage by about 22 percent in a relatively underdeveloped South China region that borders the country's manufacturing hub and has extensive links with southeast Asian nations.

After the wage hike, workers in top-tier cities in Guangxi Zhuang autonomous region now earn no less than 1,000 yuan ($160) per month, up from 820 yuan, while workers in the poorest Guangxi cities have also seen their monthly wages grow from 565 yuan to 690 yuan, officials with the regional human resources department said Wednesday.

But workers in Guangxi's factories still get less than those in neighboring Guangdong province, which has been China's thriving manufacturing hub since the first wave of market economic reforms started there more than three decades ago.

The minimum wage in Shenzhen, a boomtown close to Hong Kong, was raised to 1,500 a month in January 2012.

Severe labor shortages, sporadic strikes and rising living costs in cities have prompted wage hikes in China over the past two years. The country aims to increase the nationwide minimum monthly wage by 13 percent annually before 2015, the central government recently said.