China's newly-minted National Security Council has ordered a probe into foreign-based non-governmental organisations operating in the country, reports said Friday, in the latest sign of tightening control by the ruling Communist Party.

The "thorough investigation" -- which was launched by the security council and is apparently being administered by local governments -- began in May and will continue until the end of July, according to a report on a local party-run news portal in Yuncheng in the northern province of Shanxi.

The news comes as foreign companies and other organisations come under heightened scrutiny by Chinese authorities.

Earlier this week, a senior anti-corruption official warned that experts at the state-affiliated Chinese Academy of Social Sciences (CASS) were spreading false ideas online and allowing foreign "infiltration" in their work.

Chinese authorities have also moved to limit access to US-based search engine Google in recent weeks, while in the past year a host of foreign pharmaceutical firms including US-based Eli Lilly, Denmark's Novo Nordisk and British drugmaker GlaxoSmithKline have found their business practices placed under scrutiny, according to state media.

According to a notice released by the Yuncheng local government and posted online this week by the government-linked Yuncheng Sunlight Rural Public Integrity Network website, the probe into foreign NGOs and their relationships with Chinese partner organisations aims to "lay a foundation for further strengthening the administration of standards".

Links to the original posting appeared to have been taken down by Friday. But several other Chinese news sites posted screenshots of the notice, which stated that foreign foundations, societies, chambers of commerce, institutes and non-profit institutions would be included in the "in-depth" investigation.

The notice also advises local government officials not to speak publicly about the investigation so as to "avoid triggering domestic and foreign concern and speculation".

Neither the Yuncheng local government or the National Security Council immediately responded to requests for comment on Friday.