A Sudanese shepherd granted asylum in the UK has claimed that "immorality" in Newcastle encouraged him to sexually assault a man in the city centre.

Zain Osman, 25, who arrived in the country on a lorry, thrust his hands down the victim's trousers and tried to force him to perform oral sex on him in the street.

He also bit the man on his back and shoulder and sent him tumbling into a roadworks ditch during the 20-minute attack last September.

The attack was halted by a taxi driver who saw what was happening and intervened, Newcastle Crown Court heard.

Osman, of Gerald Street, Newcastle, admitted sexual assault and was jailed for 15 months. He was also made the subject of a 10-year sexual harm prevention order and his name will appear on the sex offenders register for the same period.

But Jamie Adams, defending Osman, said his client carried out the sexual assault because he had "never experienced the kind of immorality" he witnessed in Newcastle and that his behaviour was not violent but showed "clumsy drunken persistence".

"He is an uneducated man. He was a shepherd in his own country, the Sudan," said Mr Adams.

"He had never experienced the kind of immorality he experienced in coming here and was evident in this particular area of Newcastle.