Geneva: Swiss authorities said on Thursday they had frozen tens of millions of dollars in assets as part of an investigation into Malaysia’s troubled state investment fund, 1 Malaysia Development Berhad (1MDB).

The Swiss attorney general’s office further confirmed that criminal proceedings had been opened against two executives of the fund, which has been at the centre of mounting anger over Malaysian Prime Minister Najeeb Razak’s tenure.

Allegations have circulated for months in Malaysia that huge sums had vanished in deals with heavily-indebted 1MDB, which Najeeb launched in 2009.

“The Office of The Attorney General of Switzerland (OAG) has frozen assets amounting several tens of millions of US-dollars on Swiss bank accounts,” spokeswoman Anna Wegelin told AFP in an email.

She further explained that the criminal probes targeting the two unnamed executives related to money laundering and “suspected misconduct in public office”.

Cooperation with other countries, including Malaysia, will likely be crucial to the investigation, she said, noting that Swiss authorities had already made contact with Kuala Lumpur about the probe.

The Malaysian fund said in a statement that it had no knowledge of the Swiss action.

“As far as 1MDB is aware, none of the company’s bank accounts have been frozen.”

The fund “is in the process of developing a better understanding of the ongoing investigations in Switzerland so the company can cooperate to its fullest extent,” it added.

The prime minister and 1MDB fiercely deny any wrongdoing, but reports have mounted concerning suspect transactions, including ones possibly linked to Najeeb’s family members.

Tens of thousands of people poured into the streets in Kuala Lumpur and other cities over the weekend, part of intensifying calls for Najeeb to come clean about the financial scandals surrounding his government.

Switzerland, meanwhile, has increasingly tried to combat its global image as a country where corrupt foreign officials can hide money, freezing assets and returning huge sums previously looted from Nigeria, the Philippines and several other countries.