Oil prices are at their highest since July 2015 as a result of Saudi Arabia’s crown prince’s crackdown on corruption over the weekend.

After Mohammed bin Salman’s crackdown led to the arrests of several royals, ministers and investors, US crude CLc1 broke above $56 a barrel for the first time in more than two years on Monday, Reuters reported. Around 6.30 am Eastern Standard Time on Tuesday, it was at $57.36 a barrel. Brent crude oil was trading at $64.08 a barrel.

Saudi Arabia’s campaign against graft expanded further on Monday with the reported arrest of top entrepreneur Nasser bin Aqeel al-Tayyar. Saudi banks have also begun to freeze the accounts of many suspects, Reuters cited sources as saying. A no-fly list has also been drawn up, and private jets were not being allowed to take off from some Saudi airports without any permits, local media said.

“Yesterday does not represent the start, but the completion of Phase One of our anti-corruption push,” Saudi Attorney General Saud al-Mojeb said, adding that investigations were done discreetly “to preserve the integrity of the legal proceedings and ensure there was no flight from justice”.

Those arrested on Saturday include prominent billionaire investor Prince Alwaleed bin Talal, the National Guard head Prince Meteb bin Abdullah and Economy Minister Adel Fakeih. Prince Alwaleed bin Talal is one of the world’s richest men and holds major stakes in News Corp, Citigroup and Twitter.

They were arrested soon after a committee was formed by royal decree. The panel headed by Crown Prince Mohammed bin Salman has the power to investigate, arrest, ban from travel, freeze accounts and track funds and assets of individuals involved in corruption practices.

Mohammed bin Salman is considered the favourite son of King Salman and has been behind several reform measures the kingdom has taken in recent years. The arrests and crackdown on corruption are seen by some as an attempt to consolidate his power.