Washington: Donald Trump has lashed out at department store chain Nordstrom for dropping his daughter's clothing line, again spotlighting the intermingling of the US presidency with Trump family businesses.

The public rebuke on Wednesday, which the White House later defended, called renewed attention to the potential tangle of business interests Trump brought with him on taking office last month.

In a tweet posted moments after he wrapped up an address to US law enforcement, Trump hit out at the high-end retailer for announcing last week it had decided to discontinue sales of Ivanka Trump's fashion line due to poor sales.

Since his surprise victory in the November presidential election, Trump has used his Twitter feed to lambast individual companies -- from General Motors to Boeing -- be it for off-shoring jobs or allegedly overcharging the federal government for aircraft.

But the latest tweet was different in that it sought to defend part of Trump's family business empire, which critics have said could be a source of profound conflicts of interest for the White House.

Trump made sure to give his message on Ivanka maximum reach by posting it both on his personal handle @realDonaldTrump and on the official account of the US presidency @POTUS.

Since his November victory, Trump has touted an effort to remove himself from running his business empire, transferring corporate control to his sons. But he has resisted divesting, as a government ethics watchdog had called on him to do.

Critics say the Trump businesses still pose a significant ethical quandary.

Further playing into the running debate, Pentagon officials said on Wednesday they were looking to rent space in Trump Tower, Trump's flagship Manhattan luxury building, to accommodate equipment and staff who accompany the president during his stays there.

That came on the heels of a lawsuit filed by Melania Trump in New York, which claimed that damaging rumors reported by a British tabloid had interfered with her "unique, once-in-a-lifetime opportunity" to earn millions of dollars due to her raised profile as first lady.