BEIJING -- China on Monday voiced concern over a proposal by European Commission President Jean-Claude Juncker to create a new EU framework for investment screening.

"If a foreign, state-owned company wants to purchase a European harbor, part of our energy infrastructure or a defence technology firm, this should only happen with transparency, scrutiny and debate," Juncker said in EU address.

Chinese Foreign Ministry spokesman Lu Kang said the EU had for a long time promoted free trade and investment facilitation, which had brought real benefits to European nations.

An open world economy is in the interests of all and is an unstoppable trend, he told a routine press briefing.

"Closing the door will not achieve lasting development," he said. "The losses will outweigh the gains if people resort to protectionist trade policy for short-term interests."

Lu said he hoped the EU would respect World Trade Organization principles, especially non-discriminatory principles, in any measures it adopted.

The EU should avoid sending confusing and negative signals to the outside world, he said.