SAO PAULO, April 19 (Reuters) - A Dutch court on Wednesday ordered two subsidiaries of Brazilian phone company Oi SA to begin bankruptcy proceedings, giving some creditors a new form of leverage for their fight in Brazil's biggest-ever bankruptcy case.

The ruling, which overturned a lower court's decision in February, gives Oi the chance for a final appeal before the Dutch Supreme Court, which the company said it would request.

If Wednesday's ruling stands, court-appointed trustees for Oi Brasil Holdings Coöperatief UA and Portugal Telecom International Finance BV will be tasked with liquidating the units to repay creditors.

Oi's two Dutch subsidiaries issued about 5.8 billion euros ($6.2 billion) of debt, representing most of the company's outstanding bond debt of approximately 8.5 billion euros.

Those funds were passed largely to the parent company, which is protected from creditors by its own restructuring process in a Brazilian court, where the judge will have a say over claims from trustees of the Dutch subsidiaries.

Oi said in a securities filing that the Dutch ruling had no impact on its day-to-day operations, including sales, maintenance and investments.

In June, Oi filed for Brazil's largest-ever bankruptcy protection process, in an effort to restructure about 65 billion reais ($21 billion) of bond, bank and regulatory liabilities.

The Dutch case created an early divide among the company's bondholders. Investors such as Aurelius Capital Management LP, Attestor Capital LLC, Citadel LLP and York Capital Management formed the so-called International Bondholder Committee to press their case in the Netherlands while a group advised by Moelis & Co focused exclusively on the Brazilian case.

The International Bondholder Committee, which holds more than $2 billion of bonds issued by the two Dutch companies and other Oi units, declined to comment on Wednesday's ruling.

($1 = 3.149 reais) (Reporting by Brad Haynes and Alberto Alerigi Jr.)