In a statement released on Tuesday, Singapore Exchange Regulation (SGX RegCo) Chief Executive Tan Boon Gin said the changes enhance the standards required of auditors and property valuers in their dealings with listed companies.

"We expect the quality of the market and investor protection to improve as a result," Tan said.

The moves, effective from Feb. 12, follow market criticism faced by SGX RegCo, the city-state's frontline capital markets regulator, over its handling of accounting irregularities at some listed firms.

SGX RegCo has already stepped up disciplinary action on companies and toughened listing requirements, while also making it mandatory for firms to have a whistleblowing policy. SGX has been working to strengthen regulation and shore up liquidity after a penny stocks crash in 2013 battered investor confidence.

SGX is one of the world's biggest global listing hubs for real estate investment trusts and business trusts - a key segment for retail investors.

The regulatory unit said all primary-listed issuers must appoint an auditor registered with Singapore's Accounting and Corporate Regulatory Authority to conduct their statutory audits.

Following this new requirement, these audits will effectively be subject to the accounting regulator's oversight.

SGX RegCo may also require companies to appoint a second auditor in exceptional circumstances.

Additionally, SGX RegCo said it "will require property valuers to have at least five years of relevant practical experience in valuing properties in a similar industry and area as the property to be valued."

(Reporting by Anshuman Daga; Editing by Himani Sarkar and Kenneth Maxwell)