Gaopeng.com, a Chinese group-buying portal launched by Groupon and Tencent, fired a vice president on Wednesday after discovering that some of its employees were found to have cheated in an iPhone lottery on Weibo, the Chinese version of Twitter.

Gaopeng last week held a lottery on its Tencent and Sina Weibo sites, claiming that any Weibo users who followed Gaopeng and re-tweeted the lottery information would have a chance of winning a white iPhone 4.

The website said it would select two winners randomly on both of the two weibo services and announce them Tuesday.

Gaopeng's follower numbers surged as a result of the announcement.

However, when the "lucky winners" were announced, some followers became suspicious about the results when it emerged that the four winners on Sina and Tencent Weibo turned out to be the same two people.

Some Internet users said online that the two winners were actually Gaopeng's employees and began a human-flesh search, while others complained to Tencent.

In response to the massive number of complaints, Gaopeng on Wednesday morning made an official announcement, saying that its management team had carried out an all-night investigation on Tuesday.

"We have found that some individual employees had taken advantage of the lottery… Gaopeng has already fired a vice president in charge of the lottery… and we will offer another 20 iPhone 4s in the lottery to compensate our followers," read the announcement.