Sheridan said he was "optimistic" that his brother was "alive and stuck".

Zachary last contacted his family on April 22, when he was near Mount Everest.

More than 3200 people are reported to have died in the quake, including one Australian who was reportedly killed in an avalanche.

A total of 549 Australians were registered as travelling in the area, and some 350 remain unaccounted for.

In statement released to social media, the LA-based former Packed to the Rafters star thanked his fans for their "messages and kind words" since news broke that his brother was among the missing.

"I'm on my way to Nepal now and will head toward base camp to try and find [him]," Sheridan said.

Sheridan said he would be joining a crew equipped with a helicopter, a doctor and a satellite phone.

"So many of us are still waiting to hear but communication is down," Sheridan said, adding: "Stay positive everyone."

The 29-year-old actor issued the statement via his Instagram​ account, and posted it below the last image his brother sent from Nepal.

He also asked the media to respect his mother's privacy.

"I know that the news have been eager to talk to my mum but it would be respectful to leave her alone at this time," he said.

"My heart goes out to every family who is still waiting to hear, I can't imagine how they feel at Mount Everest.

"I'm looking forward to seeing my little brother and getting him out safely."