Los Angeles, June 17 (AZINS) Socialite Paris Hilton's younger brother Conrad Hilton has been sentenced to three years of probation for causing a disruption on an international flight.

He was also required to do 750 hours of community service and pay a $5,000 fine for his disorderly conduct, reports aceshowbiz.com.

The Hilton heir pleaded guilty in March to a misdemeanour assault stemming from a meltdown aboard a British Airways flight from London to Los Angeles on July 31, 2014. 

The 21-year-old is said to have yelled at the flight attendants and even threatened to kill them.

According to an affidavit written by an FBI agent who investigated the disturbance, Conrad was restrained and handcuffed during the flight after calling some passengers "peasants" and threatening the flight attendants. 

He also smoked marijuana and cigarettes in an airplane toilet. 

After the mid-flight outburst, Conrad voluntarily checked into a 30-day inpatient drug and alcohol treatment programme in February. 

Conrad's attorney Robert Shapiro claimed that his client's disruptive behaviour was "the effects of a sleeping pill".