FRANKFURT (Reuters) - General Motors ailing Opel brand is replacing sales chief Alfred Rieck, who is leaving the company after nearly seven months in office.

Opel named its head of Opel's UK sister brand Vauxhall, the 43-year-old Duncan Aldred, as interim head of sales and marketing on Friday.

"He's thrown in the towel," one person familiar with the situation told Reuters earlier.

Before the 56-year-old Rieck came to Opel to head up its sales and marketing operations in July last year, he was President of Volkswagen's Skoda unit in China.

(Reporting By Christiaan Hetzner)