Two 10-year-old boys from Houston, Texas, have been charged with aggravated sexual assault after allegedly sexually molesting an eight-year-old boy on a school bus.

They were arrested after a security video surfaced that allegedly showed two boys pulling down their trousers and forcing a younger boy to perform sex acts on them.

The alleged assault took place in August 2011.

If convicted, the boys, who cannot be named for legal reasons, could face up to 40 years in prison.

The alleged victim's mother told the Houston Chronicle that she remembered her son coming home from school without his belt and with his trousers unbuttoned but paid no attention to it until the police informed her that he had been molested.

She explained that her son, who already been transferred to another school, had been struggling to cope following the incident.

She told the newspaper: "He's just been having a hard time. He cries a lot."