CHARLESTON, South Carolina (REUTERS) - The US flag flew high outside a sheriff's office in South Carolina on Monday in defiance of an order from President Barack Obama to lower all flags in memory of the late South African leader Nelson Mandela.

Pickens County Sheriff Rick Clark said he believed the lowering of the flag to half-staff was a tribute that should be reserved for US citizens.

"To show a sign of respect for what Nelson Mandela's done, I have no problem with lowering it in South Africa, in their country," Mr Clark told a local television station.

"But in our country, it should be the people, in my opinion, who have sacrificed for our country." On Friday, the sheriff's flag flew at half-staff in honour of a South Carolina law enforcement officer who was killed in the line of duty and it remained lowered through Pearl Harbor Day on Saturday.

The flag was raised to the top of the mast on Monday, however, and the sheriff's office said Mr Clark would have no further comment beyond what he told a local TV reporter.

Mr Obama ordered that flags be flown at half staff until sunset on Monday.

South Carolina, in the heart of the old Deep South, has a troubled history when it comes to race relations and civil rights.

Governor Nikki Haley, a Republican and daughter of Indian Sikh immigrants, posted a tribute to Mandela on her Facebook page last Thursday.

Some commentators on the Facebook page later responded by calling Mr Mandela everything from an "evil man" and "devout Marxist" to "a socialist goon."