Donald Trump's effort to end a scheme protecting young illegal immigrants from deportation suffered a setback after the US Supreme Court declined to hear the case.

The White House had moved to end the living and working rights of 800,000 people brought to the United States as children, but that measure had been blocked by the lower courts.

The administration attempted to bypass further debate in the lower courts by urging the Supreme Court to step in and end the deadlock over the status of the so-called "Dreamers".

But the highest court declined, further throwing into confusion an already complex debate over reforms to the US immigration system.

The Dreamers are currently protected from deportation by the Obama-era Deferred Action for Childhood Arrivals (DACA) programme.

The latest legal decision means the case will now have to work its way fully through the lower courts before any eventual Supreme Court ruling is possible.

White House officials re-iterated their position that DACA was "clearly unlawful".

A spokesman said the lower courts that have so far preserved it were "usurping legislative authority".

Democrats welcomed the Supreme Court's decision but said a full resolution was still needed.

Richard Blumenthal, a Democrat senator, said: "Today's decision puts a little more time on the clock (for the Dreamers) but fails to solve the underlying problem and in no way diminishes the urgency of Congress taking immediate action."