WASHINGTON (AP) — A senior Senate Democrat is asking the Treasury Department to evaluate whether President Donald Trump and his family's business associates and possible investors from Russia and other countries have violated U.S. laws against financing terrorism, money laundering and other illicit activities.

Trump's refusal to jettison or disclose investments that create potential conflicts of interest raises concern over his extensive international holdings, Sen. Sherrod Brown of Ohio said in a letter Thursday to the new Treasury secretary, Steven Mnuchin. Brown is the senior Democrat on the Senate Banking Committee.

Brown asked Mnuchin whether he has requested or received from Trump and his family a complete list of their investors and business partners.

The Treasury Department has responsibility to enforce U.S. laws and sanctions against terrorist financing, bank secrecy and money laundering.

A Treasury spokesman didn't immediately return a request for comment Thursday.

"Given the potential conflicts with (U.S.) laws posed by the vast holdings and business activities of the president and his family, have they provided you — or have you requested from them and received — a comprehensive list of their investors, business partners, politically exposed persons and related actors?" Brown asked Mnuchin in the letter. "It is in the interest of the Trump family and the American people that Treasury independently assess any risks associated with these investors."

If he hasn't already done so, Brown asked Mnuchin to request from Trump a full list, so that the Treasury, other regulators and U.S. intelligence officials can assess the foreign partners and investors.

Brown cited a 2008 statement by son Donald Trump Jr. that Trump businesses "see a lot of money pouring in from Russia." He asked whether ownership or investment deals with Russians might allow "opportunities for economic leverage over the president or any of his family members or associates."

Trump visited construction sites and met with city officials during visits to Russia, and he presided at a Miss Universe pageant. But he didn't strike any real estate deals, though he discussed several deals in three visits dating to 1987.

Russia as well as several Russian leaders and business executives have come under international and U.S. sanctions in recent years.

Trump has been shadowed by questions about potential ties to Russia since winning the election in November. U.S. intelligence agencies have concluded that Russia meddled in the campaign in an effort to help Trump defeat Democrat Hillary Clinton. Federal investigators have been looking into possible contacts between Trump advisers and Russia.

Brown said the concerns aren't limited to Russia, noting the family-owned Trump Organization's array of investments and business ties around the world.

Through it, Trump has interests in some 500 companies in about 20 countries, forming a complex and opaque empire scattered around the globe. His holdings create a tangle of potential conflicts of interest without precedent in modern U.S. history.

Trump has his name on hotels, residential towers and resorts stretching from South Korea and the Philippines in Asia to Uruguay in South America and Turkey in the Middle East. Indonesia, Panama and India are among the other locations where he has struck deals.

Many of the Trump Organization companies have no business operations and are just shells set up to hold stakes in other companies, possibly to provide legal and tax protection. Trump owns little overseas. He has preferred to strike licensing deals that entail little more than renting out his name for hefty fees.

Ethics experts note the possibility that Trump might be tempted to shape regulations, taxes and foreign policy to enrich himself or his business partners. Foreign governments could seek to influence him by rewarding or punishing his business interests in their countries.

The experts have called for Trump to sell off his assets and place his investments in a blind trust, an entity that his family would not control. That's what previous presidents have done. Trump hasn't been willing to go that far. He has said he will not be involved in day-to-day company operations and will leave that responsibility to his adult sons, Eric and Donald Trump Jr. Trump hasn't addressed the ethical minefield of whether he would retain a financial interest in his Trump Organization.