The Los Angeles Police Department said the incident occurred at Los Angeles International Airport after Tomlinson and his girlfriend, Eleanor Calder, were "surrounded by paparazzi".

"There was some pushing and shoving and one of the paparazzi fell down," the LAPD said.

US media quoted witnesses to the incident as saying the photographer fell when Tomlinson pulled him to the ground by his legs.

The unnamed photographer struck his head on the floor and was later transported to hospital, airport police said.

In a separate altercation which took place moments later, Tomlinson is said to gave grabbed the wrist of a witness, who was recording the incident on a mobile phone.

Airport police said the witness was allegedly struck in the eye; she was later treated at the scene.

The online celebrity news outlet TMZ reported the female witness had been attempting to film Tomlinson's girlfriend when the second scuffle broke out.

"The two women allegedly then got into a physical altercation," TMZ reported.

Both altercations took place in the baggage collection area of LAX.

Billboard magazine reported the pair had been holidaying in Las Vegas which suggests the incident took place in one of LAX's domestic terminals, not the larger Tom Bradley international terminal.

The London Sun newspaper quoted an unnamed source saying that Tomlinson had asked the photographer to stop filming "but he didn't take kindly to the request."

The source said: "The row turned into a scuffle causing airport security to pull them apart."

The 25-year-old One Direction star was arrested on suspicion of simple battery.

The Los Angeles County Sherriff's Department said Tomlinson was released from custody on US$20,000 bail.

A statement from Tomlinson's lawyers was released to media, blaming the incident on the paparazzi.

"The paparazzi provoked and caused the altercation that occurred with Louis at the airport this morning," the statement said.

"This is not the first or last time that a paparazzi has created an altercation with a celebrity," it continued.

"While the altercation was going on with the paparazzi, three other individuals were attacking [Tomlinson's] girlfriend during this incident and he came to her defence."

No formal charge has been laid at this time.

Tomlinson is due to appear in Los Angeles County Superior Court on March 29.