A group of US military veterans have vowed to block construction of the controversial Dakota Access pipeline.

On the fourth day of his presidency, Donald Trump signed an executive order to expedite the construction of the pipeline.

"We are committed to the people of Standing Rock, we are committed to nonviolence, and we will do everything within our power to ensure that the environment and human life are respected," Anthony Diggs, a spokesman for Veterans Stand, told CNBC.

"That pipeline will not get completed. Not on our watch."

Standing Rock protests continue: 'Water is life'

The group has raised $37,000 (£30,000) which will go towards "basic transport of supplies and personnel".

Native American protesters vowed they would not back down after Mr Trump signed his executive order.

Lawyers for the tribe said Mr Trump’s action was done “hastily and irresponsibly”, and they will pursue legal action.

Mr Trump’s orders overturn decisions made by Barack Obama to halt the construction of the pipeline.

Protesters occupy Standing Rock reservation, North Dakota Show all 15 1 /15 Protesters occupy Standing Rock reservation, North Dakota Protesters occupy Standing Rock reservation, North Dakota A person pours a pepper spray antidote into a protester's eyes during a protest against the building of a pipeline on the Standing Rock Indian Reservation near Cannonball, North Dakota Reuters Protesters occupy Standing Rock reservation, North Dakota People swim across a river to where the police officers are standing guard during a protest against the building of a pipeline on the Standing Rock Indian Reservation near Cannonball, North Dakota Reuters Protesters occupy Standing Rock reservation, North Dakota A man holds up a ceremonial object while police officers look down from a hill during a protest against the building of a pipeline on the Standing Rock Indian Reservation near Cannonball, North Dakota, U.S Reuters Protesters occupy Standing Rock reservation, North Dakota People protest against the building of a pipeline on the Standing Rock Indian Reservation near Cannonball, North Dakota November Reuters Protesters occupy Standing Rock reservation, North Dakota Two people stand in the water of a river while police officers guard the shore during a protest against the building of a pipeline on the Standing Rock Indian Reservation near Cannonball, North Dakota Reuters Protesters occupy Standing Rock reservation, North Dakota A man stands on a makeshift bridge over a river while police officers stand on the opposite shore during a protest against the building of a pipeline on the Standing Rock Indian Reservation near Cannonball, North Dakota, U.S Reuters Protesters occupy Standing Rock reservation, North Dakota Police use pepper spray against protesters in a boat during a protest against the building of a pipeline on the Standing Rock Indian Reservation near Cannonball, North Dakota, U.S Reuters Protesters occupy Standing Rock reservation, North Dakota Police use pepper spray against protesters in a boat during a protest against the building of a pipeline on the Standing Rock Indian Reservation near Cannonball, North Dakota, U.S Reuters Protesters occupy Standing Rock reservation, North Dakota Police use pepper spray against protesters in a boat during a protest against the building of a pipeline on the Standing Rock Indian Reservation near Cannonball, North Dakota, U.S Reuters Protesters occupy Standing Rock reservation, North Dakota Tonya Stands recovers after being pepper sprayed by police after swimming across a creek with other protesters hoping to build a new camp to block construction of the Dakota Access Pipeline, near Cannon Ball, Reuters Protesters occupy Standing Rock reservation, North Dakota Dakota Access Pipeline protesters stand in the foreground and in the waist-deep water of the Cantapeta Creek, northeast of the Oceti Sakowin Camp, near Cannon Ball, N.D., Wednesday, Nov. 2, 2016. Officers in riot gear clashed again Wednesday with protesters near the Dakota Access pipeline, hitting dozens with pepper spray as they waded through waist-deep water in an attempt to reach property owned by the pipeline's developer. Reuters Protesters occupy Standing Rock reservation, North Dakota Dakota Access Pipeline protesters stand in the foreground and in the waist-deep water of the Cantapeta Creek, northeast of the Oceti Sakowin Camp, near Cannon Ball, N.D., Wednesday, Nov. 2, 2016. Officers in riot gear clashed again Wednesday with protesters near the Dakota Access pipeline, hitting dozens with pepper spray as they waded through waist-deep water in an attempt to reach property owned by the pipeline's developer. Reuters Protesters occupy Standing Rock reservation, North Dakota People who were tear gassed return to the shore during a protest against the building of a pipeline on the Standing Rock Indian Reservation near Cannonball, North Dakota, Reuters Protesters occupy Standing Rock reservation, North Dakota People yell at police officers standing on the opposite shore of a river during a protest against the building of a pipeline on the Standing Rock Indian Reservation near Cannonball, North Dakota, U.S Reuters Protesters occupy Standing Rock reservation, North Dakota Police use pepper spray against protesters in a boat during a protest against the building of a pipeline on the Standing Rock Indian Reservation near Cannonball, North Dakota, U.S Reuters

Last year, the US Army Corps of Engineers denied the permit to build the $3.8bn Dakota Access Pipeline amid months of protest outside the Standing Rock Sioux Reservation in North Dakota.