UPDATE 2-Groupon touts mobile transactions in shareholder letter

* 30 pct of North American transactions were mobile in April

* More than 170 mln Groupons sold at end of 2011

* Targeting a broad international roll-out of SmartDeals

* Shares rise as much as 8 percent

May 7 (Reuters) - Groupon Chief Executive Andrew Mason said on Monday that nearly 30 percent of its North American transactions were completed on mobile devices in April, sending the company's shares up as much as 8 percent.

The high-flying controversial company that sells online daily deals to subscribers sold more than 170 million Groupons to more than 33 million active customers by the end of 2011, Mason said in a letter to shareholders.

Mason also said Groupon was targeting a broad international roll-out of SmartDeals by the end of the year.

Groupon has come under fire for its unorthodox financial reporting in the run up to last year's closely watched IPO. It revised its fourth-quarter results in March, admitting to "material weakness in its financial statements, and in April appointed two new board directors to stave off criticism of its accounting practices. (nL1E8FUEFV).

Shares of the company were up as much as 8 percent at $10.72 on Monday morning on the Nasdaq.