The United Nations' top human rights official hailed Pescara's Ghanaian midfielder Sulley Muntari as an "inspiration" on Monday for leaving the pitch in protest after the player said he was booked for complaining about racist chanting.

U.N. High Commissioner for Human Rights Zeid Ra'ad al-Hussein said Fifa needed to pay greater attention to the persistent problem of racism at games - and that his office had been in touch with soccer's governing body.

Muntari said he had complained that parts of the crowd, including a group of children, had hurled racist insults at him from the start of his Italian team's game at Cagliari in Serie A on Sunday.

The player said the referee then told him to stop talking to the crowd and ended up showing him the yellow card for dissent in the 90th minute.

Zeid called Muntari "an inspiration to all of us here at the U.N. human rights office" for taking a stand.

The persistent problem of racism at games required "added attention or deepened attention by Fifa," he told reporters in Geneva.

His office had been in touch with the organisation, he said without saying when, and he planned to attend an international match in about six weeks' time to spread the message that "racism and expressions of bigotry should not be tolerated at major sporting events".

Zeid recalled another "deeply alarming" match, in Ukraine, where Dynamo Kiev fans wore Ku Klux Klan outfits and swastikas.

Italy and other countries have struggled to stamp out racist chants at games. In 2013, the AC Milan team left the pitch during a friendly in the town of Busto Arsizio after home fans insulted midfielder Kevin-Prince Boateng, another Ghanaian.

Under guidelines introduced following that incident, the referee is supposed to alert the fourth official who should in turn contact authorities policing games.

Fifa last week fined Argentina, Mexico and Brazil for their fans' homophobic chants - sign of a growing crackdown on the insults often hurled at opposing goalkeepers.