No. 1 daily deals website Groupon Inc is turning to executives from Citydeal -- the European business it bought last year -- to help boost slowing growth in its domestic business, ahead of a planned public listing.

The company appointed Christopher Muhr as its sales chief, taking over from Darren Schwartz, a source familiar with the matter who did not want to be named, said.

Muhr is moving from London where he was managing director of Groupon UK.

Also joining Muhr at the company's Chicago headquarters are members of the international management team, including fellow Citydeal co-founders Rajen Ruparell, Emanuel Stehle and Jens Hutzschenreuter.

Germany's Citydeal, which Groupon bought last year, was used by the company to kick-start its international operations.

The changes were communicated to Groupon employees last week, the source said.

When contacted, a Groupon spokeswoman did not immediately confirm the appointments.

The move seems aimed at tapping into the strength of the company's international team, which has helped grow overseas sales significantly.

Groupon, which offers group-buying deals on everything from spa treatments to flying lessons, saw its subscriber base more than double to 115 million this year.

However, growth has slowed recently as its domestic market starts to mature. Revenue was up 36 percent in the second quarter, down from the 63 percent increase it posted in the first quarter.

Revenue per subscriber fell 12 percent to $8.57 in North America, according to Yipit, which tracks the daily deal industry.

Founded in 2008 by Northwestern University music major Andrew Mason, Groupon has filed to raise up to $750 million in an IPO, expected to be one of the most high-profile new listings of 2011.

(Reporting by Nivedita Bhattacharjee in Bangalore; Editing by Anthony Kurian)