WASHINGTON (REUTERS) - Mr Donald Trump on Tuesday ratcheted up attacks on Tesla chief executive officer Elon Musk, after Mr Musk said Mr Trump was too old to become the next United States president and needed to "sail into the sunset".

The former US president said Mr Musk would have "begged" him for government subsidies, in a message on his own social media app, Truth Social.

"When Elon Musk came to the White House asking me for help on all of his many subsidized projects, whether it's electric cars that don't drive long enough, driverless cars that crash, or rocket ships to nowhere, without which subsidies he'd be worthless and tell me how he was a big Trump fan and Republican, I could have said, "drop to your knees and beg, and he would have done it," Mr Trump wrote.

In response, Mr Musk tweeted, "Lmaooo" - shorthand for "laughing my ass off".

Mr Musk said on Monday: "I don't hate the man, but it's time for Trump to hang up his hat and sail into the sunset."

Mr Musk, who previously said he was leaning towards supporting Florida Governor Ron DeSantis for president in 2024, said Mr DeSantis would easily defeat President Joe Biden in the election.

Mr Musk's remarks were in response to comments Mr Trump made at a political rally last Saturday where he called Mr Musk a "bull***t artist" for claiming that he had never voted Republican until this June.

"He told me he voted for me," Mr Trump said.