Republic of Doyle star Allan Hawco has fuelled a social media campaign against a controversial fence that will bar public access to much of the St. John's waterfront.

Hawco, who also created and produces the CBC series, said he was appalled when he learned of the magnitude of the fence on Thursday, after new drawings of the fence became public and showed that much of the stretch along Harbour Drive will be enclosed.

"I didn't really realize the severity of it, like most of us," said Hawco, who issued a series of tweets that helped make the #stoptheharbourfence hashtag a trending topic on Twitter.

One of Hawco's tweets on the subject on Thursday evening had been retweeted almost 200 times by Friday morning.

The St. John's Port Authority plans to erect a permanent fence for security reasons, citing the need to protect commercial shipping connected to the offshore oil industry and with cruise ships sailing from foreign ports.

Hawco, whose show often has scenes set along various parts of the waterfront, said he is worried that residents of St. John's do not appreciate what is at stake.

"We have this beautiful town that people from all over the world come to see and when they get here they're in awe about how beautiful and unique it is," Hawco told the St. John's Morning Show Friday.

"A big centre piece of that is obviously the harbour. That's our harbour that we've had access to since the dawn of North America."

Hawco, who said he was "cringing" about becoming involved in a political issue, said he felt motivated to speak out about what he sees as a threat to something many people take for granted.

One of Allan Hawco's tweets from Thursday evening was retweeted dozens of times. (CBC)

"Public access will be reduced to almost nothing. I find that very bizarre," Hawco said.

Coun. Sheilagh O'Leary spoke out Thursday about the plans after attending a meeting, where she said it had become clear that what the Port Authority had in mind was beyond what council had expected.

The Port Authority is asking city council to cover half of the costs of the new fence, which will replace a temporary chain-link fence that was installed a few years ago near the pier where cruise ships often dock.

Council agreed in early September to pick up the expense. "The current fence is hideous," Mayor Dennis O'Keefe said at the time.