An appeal to find a missing German cyclist riding through Mexico gained traction on Thursday, with Facebook users sharing posts and possible sightings.

Holger Franz Hagenbusch's brother took to the social media platform on Sunday after failing to hear from the cyclist for 11 days.

"He is cycling in Mexico. His last location was San Cristobal. His destination was Ciudad del Carmen, but he never arrived there," said Rainer Hagenbusch in his Facebook post.

"The Federal Criminal Police Office, the German embassy and the Mexican embassy are involved. Please share this message with everyone living in Mexico."

Mexican journalist Ciro Gomez Leyva circulated a video that showed images of Holger Franz on his journey through Mexico.

'We're going to find Holger'

A Facebook page dedicated to the search has received hundreds of interactions since its first post on Tuesday.

"Today is Holger's birthday! The greatest gift would be that he can return home safe and sound," campaign organizers said in a post on Wednesday. "We're going to find Holger."

Although Hagenbusch has traversed Eastern Europe, Central Asia and the Middle East, his desire to travel originated in South America during a trip through the Andes Mountains, according to a blog post.

The 43-year-old cyclist was planning to travel throughout Latin America, after which he would continue to Africa.

"You can only really experience foreign countries without the pressure of time," Hagenbusch wrote in a blog post for German biking supply manufacturer Mainstream MS-X. "So I let myself be inspired locally by the locals and experience what is happening right in front of the wheels."

Mexican authorities established a hotline for tips at +512 (442) 3835821.