Singapore on Monday said US officials invited to inspect the work of a local research institute allegedly linked to a Chinese telecoms firm which Washington suspects of espionage were "satisfied" with the audit findings.

The state-linked Institute of Microelectronics (IME) was first thrust into the spotlight in February when the London-based Financial Times cast doubt on the apparent suicide of one of its former researchers -- US electronics engineer Shane Todd, who was found hanged in his Singapore flat in June 2012.

It said his family suspected he was murdered because of his work on a joint IME project with Huawei Technologies involving gallium nitride, a semiconductor material with military and commercial applications.

Singapore's foreign ministry said in a statement Monday that US officials had completed a "process audit" at the IME, after being invited to do so following allegations it was involved in an improper transfer of technology with Huawei.

"The US officials who came for the audit were satisfied with the audit," the ministry said in the short statement.

Huawei -- accused by US officials of involvement in espionage -- and IME said they had only held preliminary talks on a potential project with commercial applications, but had not gone further.

A state coroner subsequently ruled in July that 31-year-old Todd committed suicide during a bout of depression, debunking his family's conspiracy theory.

The family attended the coroner's inquest in May but angrily walked out after six days and flew home, saying they had "lost faith" in the proceedings.

The US government said in July the two-week enquiry was "comprehensive, fair and transparent".

The foreign ministry said the audit had been offered to US officials by IME on a "voluntary basis".

It said the offer had been conveyed to Secretary of State John Kerry by Foreign Minister K. Shanmugam during a visit to Washington in March.

The offer was made "in the spirit of cooperation and openness to satisfy the US that allegations of illegal transfers of US technology from IME to the Chinese company Huawei were completely untrue and without basis", the ministry said.

Singapore is a longstanding military partner of the United States. The US military operates a post in the city-state that assists in logistics and exercises for its forces in Southeast Asia.