BEIJING (REUTERS) - Chinese weather forecasters warned on Wednesday (June 29) that the first typhoon of the summer appeared to be forming, bringing rain and unsettled weather to southern China, ahead of the 25th anniversary of Hong Kong's handover to the mainland.

Chinese President Xi Jinping will visit Hong Kong for the anniversary on Friday of the 1997 handover of the former British colony, the Xinhua state news agency has reported.

A tropical depression in the South China Sea is likely to develop into a typhoon within 36 hours and move in Hong Kong's direction, from the east of Hainan Island to the west of Guangdong province, the national meteorological centre said in a morning typhoon bulletin.

The Hong Kong Observatory said the low pressure in the central part of the South China Sea had intensified into a tropical depression that would approach to within 800km (500 miles) of Hong Kong on Wednesday, according to its expected path.

"Depending on local wind changes, the observatory will consider issuing the Standby Signal No. 1 tonight," it said, referring to the city's lowest storm warning.

The coastal province of Guangdong, China's most populous province with about 126 million people, was this month inundated with rain that brought flooding as summer thunderstorms lashed China's south.

Gales in the South China Sea, off Guangdong's east coast and near the Paracel Islands, were forecast to reach moderate magnitudes of 6-7 but the wind in some parts of the sea could be stronger, the forecasters said.