PHNOM PENH (REUTERS) - Cambodian Prime Minister Hun Sen, under Western donor pressure over a crackdown on his critics ahead of 2018 elections, will seek more aid and investment from China during a visit this week, his aide said.

Mr Hun Sen's aide, Sry Thamrong, said the prime minister will attend a special summit on Nov 30 to Dec 3, which will be held by Communist Party of China (CPC) with political parties from over 100 countries.

Mr Hun Sen will also meet Chinese President Xi Jinping and Chinese investors to talk aid and investment with the aim of creating more jobs in Cambodia, Mr Sry Thamrong said.

"Especially, we need more bridges on the Mekong River, we also need many more roads, trains, sky trains, these are the things that we need in the future," Mr Sry Thamrong told reporters at Phnom Penh International Airport before his departure.

China is already the country's biggest donor and its support has bolstered Mr Hun Sen in the face of criticism of what his opponents say amounts to the destruction of democracy.

The opposition Cambodia National Rescue Party (CNRP) was banned earlier this month by the Supreme Court at the government's request. That followed the arrest of its leader Kem Sokha for plotting to take power with American help.

The United States has stopped election funding ahead of next year's general election and threatened further concrete steps. The European Union has raised a potential threat to Cambodia's duty-free access.

China has supported Cambodia's crackdown, making no criticism of the government, which is one of Beijing's most important allies in South-east Asia after more than three decades in power.