(REUTERS) - A British tourist who caused a security scare at a Donald Trump campaign rally in Las Vegas in June by trying to grab a gun from a police officer pleaded guilty on Tuesday (Sept 13) to charges of illegal weapon possession and disorderly conduct, court papers showed.

Michael Steven Sandford, 20, admitted as part of his plea deal with prosecutors that he had approached a policeman at the event, saying he wanted an autograph from the presidential candidate, then tried to pull the officer's gun from his holster with both hands, the papers said.

Sandford, who had by then overstayed his tourist visa by about 10 months, was immediately arrested and removed from the rally.

He also acknowledged having visited a Las Vegas gun range the day before the June 18 incident at the Treasure Island casino-hotel, to take shooting lessons with a rented Glock handgun, firing 20 rounds at a paper target, court papers showed.

No mention was made in the plea agreement about whether Sandford intended to harm Trump, then the presumptive Republican nominee in the US presidential race.

In the initial June 20 criminal complaint stemming from the incident, prosecutors said Sandford had told a US Secret Service agent he had driven to Las Vegas from California with the aim of shooting Trump.

On June 29, Sandford was charged with felony counts of being an illegal alien in possession of a firearm and disrupting government business, but he was not accused of plotting to kill Trump.

At Tuesday's hearing in federal court in Las Vegas, Sandford pleaded guilty to those two charges, each of which carries a maximum penalty of 10 years in prison and a US$250,000 (S$341,670) fine, the US Attorney's Office said in a statement. Sentencing is scheduled for Dec 13.

Ms Brenda Weksler, one of Sandford's federal public defenders, declined to comment.