Manthi Wickramasooriya specialises in international commercial arbitration and commercial litigation, with over a decade of experience managing some of the most complex and high stakes international disputes.
Manthi has extensive experience litigating at all levels of the English courts, including the Supreme Court. He has managed international arbitrations under all major arbitral rules (including ICC, LCIA, SIAC, HKIAC, DIAC and ICSID) and most of the major arbitral seats (London, Paris, Singapore, Hong Kong, and Dubai). His work spans a broad range of industry sectors, including financial institutions, technology, infrastructure, telecommunications, and energy. He has particular expertise in M&A-related disputes and disputes arising from cross-border investments. Having also practised in Hong Kong, Manthi has substantial experience in APAC and cross-border China related disputes.
Manthi is a Fellow of the Chartered Institute of Arbitrators and was recognized as a “Rising Star” for International Arbitration by Legal 500 UK in 2024 and 2025. He is widely published in international arbitration and public international law, including a chapter on ‘Restructuring Investments to Achieve Investment Treaty Protection’ in the Kluwer volume celebrating the first 50 years of ICSID.
He holds an MA (Hons) in Law from the University of Cambridge, where he was a Commonwealth Trust Scholar.
- Ameriprise Financial, Inc
- BluStone Management
- CMIS Group
- DP World
- M1 Group
- Meridian Capital
- NMC
- Titan Trust Bank
- Union Bank of Nigeria PLC
- Counsel to two private equity firms in a $700m English law governed SIAC arbitration against a major global private equity firm arising out of the sale of a telecommunications business in Asia.
- Counsel to the buyers of a major African conglomerate in a $350m ICC arbitration concerning alleged breaches of an SPA over the sale of an African bank.
- Counsel to a NYSE listed company in an LCIA arbitration arising out of the acquisition of a major UK asset management firm.
- Counsel to technology investors in a UK start-up venture concerning allegations of fraudulent misrepresentation and defending minority rights litigation.
- Counsel to a major global port operator in an ICC arbitration against a European sovereign relating to a port concession agreement.
- Counsel to a Fortune 500 company in a HKIAC arbitration arising from the failed sale of a Chinese tech company to a Chinese asset management fund.
- Counsel to a large global carmaker in two arbitrations before the Dubai International Arbitration Centre and an arbitration before the Japanese Commercial Arbitration Association concerning a global distribution agreement.
- Acting for a Chinese VC fund in a HKIAC arbitration arising from the failed investment in a well-known cryptocurrency exchange.
- Acting for the State Savings Bank of Ukraine, in its USD 2 billion landmark UNCITRAL treaty arbitration against the Russian Federation relating to the loss of its investments in Crimea resulting from the internationally condemned annexation of that territory.
- Acting for the Ministry of Finance of Ukraine, in its major USD 3 billion dispute pending before the English Courts against the Russian Federation.
- Acting for five international hedge funds and pension funds in USD230 million English High
- Court proceedings against a Turkish construction conglomerate and its directors.
- Acting for the Defendants in Peretz Winkler & anr. v Angela Shamoon & ors. [2016] EWHC 2017(CH).
- Acting for the Islamic Republic of Pakistan in a USD2 billion ICSID arbitration brought by a Turkish power generator under the Pakistan-Turkey bilateral investment treaty.
- Acting for a premier international investment bank in a USD90 million SIAC arbitration relating to allegations of mis-selling complex derivatives products.
- The College of Law
(Legal Practice Course, with Distinction, 2010) - University of Cambridge, Fitzwilliam College
(M.A. (Cantab), Law, with Honors, 2009)
- Solicitor, England and Wales
- Sinhalese
- Allen & Overy, LLP
- Senior Associate, 2018-2020
- Associate, 2012-2014
- Named a "Leading Associate" in International Arbitration by Legal 500 UK, 2025.
- Named a "Leading Associate" in Public international law by Legal 500 UK, 2025.
- Recognized as a Rising Star in International Arbitration by Legal 500 UK, 2024.
- Breach but no damage in ICSID arbitration (Urbaser v Argentina), LexisNexis, Feb. 2017
- Restructuring Investments to Achieve Investment Treaty Protection, Building International Investment Law: The First 50 Years of ICSID, by S. Jagusch, A. Sinclair and M. Wickramasooriya, Dec. 2015
- A Comparison of ICSID and UNCITRAL Arbitration for Investment Arbitration, Croatian Arbitration Yearbook, 20th vol., by Jeffrey Sullivan and M. Wickramasooriya, Dec. 2013
- Case Note on PT Prima International Development v Kempinski, Mealey’s International Arbitration Report, by Shobna Chandran and M. Wickramasooriya, Sept. 2012
- Fellow, Chartered Institute of Arbitrators
- Member, International Bar Association (IBA)
- Member, London Court of International Arbitration (LCIA)