April 26 (Reuters) - A subsidiary of a 100-year-old London-based tobacco company has pleaded guilty to selling and manufacturing products in North Korea in violation of US sanctions and bank secrecy laws, court documents and press statements released on Tuesday reportedly showed.

British American Tobacco (BAT) admitted evading a ban on doing business with the People's Republic of Korea - which is sanctioned for producing weapons of mass destruction - and causing US banks to inadvertently dispose of hundreds of millions of dollars of its profits.

BAT and the federal government reached a deferred prosecution agreement - if BAT continues to comply with the law, the charges will eventually be dropped - but the company will still be fined $635,241,338, the company announced.

A press release disclosed that an indirect subsidiary of the company based in Singapore pleaded guilty to three federal charges, including conspiracy to commit bank fraud and other North Korea-related laws.

Assistant Attorney General Matt Olson, who is in charge of the Justice Department's National Security Division, said it was the largest North Korea sanctions-related case in U.S. history.

According to criminal documents filed in federal court in Washington, DC, BAT and its subsidiaries maintained control of the joint venture they formed with North Korea Tobacco between 2009 and 2017, despite a 2007 announcement indicating they had sold all of the company's equity in compliance with international law.

To perpetuate the scheme, the companies admitted to building a global network of front companies and financial institutions to funnel goods and supplies into North Korea while squeezing money out.

Despite BAT's assertion that it no longer works with North Korean tobacco companies, court papers allege that it still retains significant influence over the business and uses shell companies and unnamed middlemen to continue to reap profits from North Korean sales.

Bat also exported tobacco to the North Korean embassy in Singapore until 2017, US officials said.

Three witnesses told investigators about BAT and its Singapore subsidiary working with North Korea, according to charging documents. One person told prosecutors that the company continued to supply all the raw materials needed to make tobacco products.

Another accused BAT of creating the appearance of alienation from its North Korean business partners while profiting from it.

We deeply regret the misconduct in our historic business activities that led to these settlements and acknowledge that we fell short of the highest standards expected of us, BAT Chief Executive Jack Bowers said in a statement Tuesday. Upholding strong compliance and ethical standards has been, and remains, a top priority for BAT. In recent years, we have changed our compliance and ethics program, which includes sanctions, anti-bribery, anti-corruption and anti-money laundering.

The Justice Department said BAT had fixed certain deficiencies in its corporate monitoring system and would report back to the department over a period of time to ensure compliance with the law.

Also on Tuesday, the Justice Department unsealed indictments against four people accused of aiding the illegal sale of tobacco products in North Korea. The charging documents allege that North Korean financiers Sim Hyon-Sop and Jin Guanghua and Chinese nationals Qin Guoming and Han Linli were involved in an illegal scheme to buy materials needed to manufacture and subsequently sell tobacco products.