A trader in Singapore has been charged with buying a share in the Chinese P600 trading exchange.

The accused, who was identified only by the name ‘Peng’, was arrested by the Singapore Securities and Investment Commission (SSIC) on Thursday.

His name was also mentioned in a news report about a US Securities and Exchange Commission (SEC) investigation into the alleged rigging of P600 markets.

The SEC said in a statement on Friday that the US regulator was “conducting a preliminary investigation” into the matter and that it was cooperating with Singaporean authorities.

The alleged trading activity is “particularly concerning” because it violates US sanctions on China and the “importance of our mutual economic cooperation”.

The P600 exchange, based in Singapore, was suspended in January after trading was halted due to a massive computer virus outbreak.

Its main exchange is the P5 China, which is used by the US, Australia, Canada and Hong Kong.

The US and other countries have accused China of manipulating the exchange.

Singapore was the last of the five P5 members to suspend trading in January.

The latest suspension came after a report in Reuters claimed that the exchange had been manipulated by China.

A Chinese official told the newspaper the report was “unfounded”.

The suspension was suspended “to prevent manipulation”, the official told Reuters, without specifying the source of the report.

The P5’s suspension is based on the investigation into how P600 was manipulated.

A spokesperson for Singapore’s Financial Services Commission (FSSC) told Al Jazeera that the government had not commented on the reports.

It was not immediately clear if the charges had been confirmed.

A person familiar with the matter said the case had been referred to the SEC.

The arrest of the suspect was the second of its kind this week.

On Tuesday, the SEC issued a subpoena for records of the trading accounts of P200 trading pairs.

The regulator said it wanted records of P500 trading pairs and was seeking to obtain any relevant documents, including documents relating to transactions between the P200 and P500 exchange pairs.

A P200 exchange is linked to P5 exchanges, while the P500 pairs are linked to the P50 exchange.

SEC Chairwoman Mary Jo White said the agency was seeking records related to the trading of P5 pairs, including the amount and types of trades made on those pairs.

She said it was looking for any documents “that would identify any transactions that appear to have occurred on the P550 and P550 exchange pairs, as well as transactions made on the exchanges’ P600 pairs”.

Al Jazeera’s Jonathan Head, reporting from Singapore, said there was little doubt that trading on P600 had been heavily manipulated by Chinese state-run media.

“The whole point of this is to try to get these guys to cough up their P600 shares,” he said.

“And if they don’t, you’ve got to wonder whether it was a ploy or just a ploy to get their P500 shares back.”

In its statement, the Singaporean SSC said it had been contacted by the SEC but had not received any response.