WASHINGTON (Reuters) - Euronet Worldwide Inc EEFT.O ramped up its fight against China's Ant Financial Services Group in trying to acquire MoneyGram International Inc MGI.O, urging the U.S. government to closely scrutinize the rival Chinese bid saying it raises "significant national security risks."

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In a March 27 letter to Treasury Secretary Steven Mnuchin, Euronet Chief Executive Officer Michael Brown said MoneyGram’s new owner would be asked to help law enforcement efforts aimed at combating “terrorist financing” and money laundering by complying with data requests that are often highly confidential.

“A money transfer company’s ownership and leadership at the top are critical in ensuring that all of these responsibilities are carried out fully and effectively,” Brown said in the letter, which was also sent to more than a dozen congressional offices and reviewed by Reuters.

“We feel... there are significant national security risks that merit careful evaluation for any foreign buyer of a company in this industry,” he said.

Euronet offered $1 billion for MoneyGram in mid-March, arguing that an all-American deal would face less regulatory scrutiny than the $880 million offered by Ant Financial, an affiliate of Alibaba Group Holding Ltd BABA.N. MoneyGram said Euronet's offer was potentially superior to its existing agreement with Ant Financial, but has not yet endorsed it.

The bidding war comes at a time of rising tensions between China and the United States, with U.S. President Donald Trump accusing China of unfair trade policies and criticizing its increasingly assertive stance in the South China Sea.

Mnuchin’s Treasury Department chairs the inter-agency Committee on Foreign Investment in the United States (CFIUS), which also includes the departments of Defense, Justice and Homeland Security, among others. It assesses potential mergers to ensure that they do not jeopardize national security.

The CFIUS has been a stumbling block for several Chinese deals in the United States and was considered a big hurdle for Ant Financial.

Euronet declined to comment on the company’s letter, said spokesman Pat Tucker. The Treasury Department declined comment. A representative for Ant Financial could not be immediately reached for comment.

Brown said Ant Financial’s bid merited a “close” CFIUS evaluation because money transfer companies obtain substantial personal and financial information on customers, including U.S. government employees. This information includes a customer’s name, address, social security and other identification numbers.

A new owner also would need to assist U.S. efforts to combat terrorism financing or money laundering, by reporting suspicious activity, complying with subpoenas and requests to locate accounts and transactions, Brown said.

Euronet has “consistently embraced and prioritized compliance,” he said in the letter.In recent years, U.S. authorities have increasingly held money transfer companies responsible when criminals process transactions.

In January, Western Union Co WU.N agreed to pay $586 million to settle allegations that it failed to prevent criminals from using its service for money laundering and fraud.

MoneyGram has had issues in the past. A U.S. criminal investigation revealed in 2012 that MoneyGram had processed thousands of transactions for fraudsters who were scamming the elderly. MoneyGram admitted to money laundering and wire fraud violations and agreed to pay $100 million.

MoneyGram, along with Western Union, has long dominated the global money transfer industry with its large network of retail locations. It has about 350,000 outlets in retail shops, post offices and banks in nearly 200 countries and territories.

Euronet has four money transfer businesses, including Ria, IME, HiFX and XE. Euronet’s Ria is in 146 countries, according to its website. Euronet focuses more on independent agents, while MoneyGram targets large retailers and national post offices.