WASHINGTON, May 14 (UPI) -- Twelve American ecotourists who went missing in China after Monday's earthquake are safe and accounted for, World Wildlife Federation officials said Wednesday.

The organization said the 12, who had been on a World Wildlife Federation-sponsored tour of China's Wenchuan region when the temblor struck, made contact with officials via satellite phone Wednesday. However, the group said two of its own Chinese volunteers remained missing and concerns about their safety were growing.

The American tourists were visiting a panda-breeding facility at the Wolong Nature Reserve when the earthquake struck and had not been heard from since, officials said, the wildlife organization said in a news release. It received word Wednesday morning from officials at the nature reserve that the ecotourists were all right.

"While we are relieved by this positive news about our travel group, we remain deeply concerned about our missing volunteers and the devastating impact this earthquake is having on the people of China," World Wildlife Federation officials said. "Our thoughts and prayers are with all those who have suffered such terrible losses."