Doha, which has faced an economic and diplomatic boycott by Gulf rivals since June 2017, also filed legal action in London against the Luxembourg-based Banque Havilland.
"A lawsuit was filed against Banque Havilland in London for its role in designing a plan to attack Qatar's currency and its financial markets," a statement said.
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"A separate lawsuit was filed in New York against two financial institutions that engaged in financial market manipulation," the statement said.
Both countries, along with Bahrain and Egypt, are involved in the boycott of Qatar, accusing it of backing radical groups and seeking closer ties with Iran, Saudi Arabia's arch-rival.
Doha has repeatedly denied the claims and accused its rivals of seeking government change.
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The lawsuits were filed based on an investigation launched by Doha into market manipulation, according to the statement, which said further legal action may be taken as the probe was continuing.
Qatar has already taken legal action against the four countries before the International Court of Justice, International Civil Aviation Organisation and World Trade Organisation.
Doha claimed that the boycotting countries' actions "were designed to destabilise Qatar's currency and financial markets in order to undermine confidence in Qatar's economy."
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