VIENNA Saudi National Bank wanted to increase its stake in Credit Suisse to around 40% from 9.88%, but was prevented from doing so by Swiss regulator FINMA, Blick newspaper reported on Sunday.

With Switzerland's second-largest bank on the edge of collapse, UBS agreed to buy Credit Suisse for a knockdown price of three billion Swiss francs ($3.4 billion) on March 19 in a rescue orchestrated by Swiss authorities.

FINMA must give its approval for a foreign investor to take a stake of more than 10% in a major Swiss bank.

It was not clear why FINMA opposed the move that would have involved Saudi National Bank, which was already the biggest shareholder in Credit Suisse, pumping $5 billion into the bank, Swiss newspaper Blick reported, without identifying its sources.

Credit Suisse declined to comment. FINMA and Saudi National Bank were not immediately available for comment.

UBS completed the emergency takeover of Credit Suisse last month, forging a Swiss banking and wealth management giant with a $1.6 trillion balance sheet and overseeing more than $5 trillion in assets.

The deal converted Saudi National Bank's stake in Credit Suisse into just 0.5% of UBS.

($1 = 0.8882 Swiss francs)

(Reporting by Francois Murphy; Additional reporting by Rachna Uppal in Dubai; Editing by Alexander Smith)