Billionaire entrepreneur Elon Musk has slammed Donald Trump's Nasa bill on Twitter after a user suggested Musk's own space exploration project would benefit.

Kara Swisher, co-founder of technology news website Recode, said the president's decision to grant Nasa $19.5 billion (£15.6 billion) in funding would leave Musk 'smiling.'

Musk, whose company SpaceX company is planning its own mission to Mars, replied: 'I am not. This bill changes almost nothing about what NASA is doing. Existing programs stay in place and there is no added funding for Mars.'

Billionaire entrepreneur Elon Musk lashed out at president Donald Trump's Nasa bill, signed on Tuesday, in response to a message suggesting he would be happy with the bill. He claimed that the bill 'changes almost nothing' about Nasa's existing programmes and funding

'Perhaps there will be some future bill that makes a difference for Mars, but this is not it,' Musk added in a later tweet.

Trump's S.442 funding bill, signed yesterday, is the first of its kind to pass through Congress in six years.

The law said that manned missions to deep space, including to Mars, would be the US space agency's main goal in the decades to come.

According to the text - adopted by a rare unanimous vote in the Senate and House of Representatives - NASA will work toward the goal of 'a crewed mission to Mars in the 2030s.'

The law also highlights the importance of the deep space capsule Orion, which is under development and aims to carry humans further into space than any spaceship ever has.

Orion will be launched atop the 'Space Launch System' (SLS), which the space agency has described as the most powerful rocket ever built.

In a later tweet Musk claimed that Trump's Nasa bill makes no difference for Mars missions. Trump's S.442 funding bill, signed on Tuesday, is the first of its kind to pass through Congress in six years

Musk (left) has his own space exploration company 'SpaceX', based in Hawthorne, California. The company is planning its own manned mission to Mars before 2030. Musk and Trump met in December at a summit of tech leaders to discuss the industry under Trump's presidency

Signed into law: NASA astronauts Chris Cassidy and T.C. Dyson presented the president with his own flight jacket from the agency

NASA 'shall continue the development of the fully integrated Space Launch System, including an upper stage needed to go beyond low-Earth orbit, in order to safely enable human space exploration of the Moon, Mars, and beyond over the course of the next century,' said the text.

This law reaffirms 'our national commitment to the core mission of NASA,' Trump said, signing the text in the presence of numerous elected officials including former Republican rivals, Senator Ted Cruz of Texas and Senator Marco Rubio of Florida.

He saluted the 'heroic role' of US astronauts over the last several decades, and called for continued partnerships between NASA and the private sector in the realm of space exploration.

Former president Barack Obama also hailed these industry-government partnerships, and said in October, just months before leaving office, that the United States had 'set a clear goal vital to the next chapter of America's story in space: sending humans to Mars by the 2030s and returning them safely to Earth.'

Experts say that sending people to live on the Red Planet, which lies on average some 140 million miles (225 million kilometers) away from Earth, will take immense amounts of technological advances and cash.

And here's how we will get there: An artist's impression of how Orion could look as it passes the moon - one of the stages in the mission to Mars

Land ahoy: The manned mission to mars would follow in the path of other missions, including the one which produced this NASA image of President Donald Trump on Tuesday signed a law that said manned missions to deep space, including to Mars, would be the US space agency's main goal in the decades to come.

Biggest rocket ever: This is how Orion is projected to bring its mission to Mars - blasted into orbit around the earth with more force than any previous space mission