Switzerland’s Office of Attorney-General (OAG) said Monday that Malaysian Prime Minister Najib Razak is not a suspect into the $4 billion probe of 1Malaysia Development Berhad (1MDB), a state-run fund that has been embroiled in controversy since last year.

The OAG opened criminal proceedings last August against two former 1MDB officials after it found possible violations of Swiss law related to bribery of foreign officials, misconduct in public office, money laundering and criminal mismanagement at the fund.

"In the ongoing criminal proceeding of the OAG, Najib Razak is not one of the public officials under accusation,” OAG spokesman Andre Marty told the Nikkei Asian Review, according to the Straits Times. He added the phrase “persons unknown,” which means that a crime has been committed, but the accused is unknown.

Meanwhile, Malaysia’s Minister of Communications Salleh Said Keruak accused Switzerland of breaking protocol and spreading misinformation over reports that alleged millions had been stolen from Malaysia’s state-owned companies. The issue has now led to a diplomatic rift between Switzerland, one of the countries investigating the corruption at 1MDB, and Malaysia.

“These premature statements appear to have been made without a full and comprehensive appreciation of all the facts,” Salleh told the Guardian, adding: “It’s very unusual, and against normal protocol, for a senior official of one country to speak publicly on the internal matters of another country. Yet that is what the Swiss Attorney General has done.”

Salleh also said: “As anyone following developments related to 1MDB is well aware, the company has issued statement after statement — providing detailed explanations, and a breakdown of its financials — to address questions that have previously been raised about these alleged losses.”

Marty reportedly said that the OAG will not respond to “political statements,” but added that his office “took note with satisfaction of the reaction of its Malaysian counterpart and of its commitment to fully support Switzerland’s request for mutual assistance.”

On Friday, the OAG said in a statement that there had been embezzlement related to $4 billion from 1MDB, and that its investigators found “serious indications that funds have been misappropriated.” The OAG also said that a part of the money was “transferred to accounts held in Switzerland by various former Malaysian public officials and both former and current public officials from the United Arabic Emirates.”

Swiss Attorney-General Michael Lauber said last week that he had requested Malaysia to help with the probe into possible violations.

The request came after Malaysian Attorney-General Mohamed Apandi Ali cleared Najib last Tuesday of any wrongdoing into the transfer of $681 million found in his personal account. Apandi added that the money was a donation from the Saudi royal family and agreed to cooperate with the Swiss investigations.

Allegations against Najib were first made in a report by the Wall Street Journal last year, which said that investigators had traced the money from an account at Falcon Private Bank in Singapore to accounts in Malaysia. The accounts were believed to be held by Najib, who founded 1MDB in 2009. Following this, some members of opposition and protesters called for the prime minister's resignation. Najib has, however, repeatedly denied the accusations.

The probe also led Singapore to seize several bank accounts in the past couple of months, as a part of its investigation into possible money laundering. The Monetary Authority of Singapore (MAS) and Commercial Affairs Department said that Singapore was cooperating with authorities in Malaysia, Switzerland and the United States, who are also investigating 1MDB.

However, 1MDB said in a statement released late Monday that it has not been contacted by any “foreign legal authorities on any matters relating to the company,” Reuters reported.