Alberta's Solicitor General Fred Lindsay is suggesting that harsher punishment could be on the way for protesters who break into oil and gas facilities.

"If they're preparing for more then they can be prepared to spend more time in remand centres," said Lindsay.

This comes after a Greenpeace protest at the Shell Scotford site in Fort Saskatchewan ended Sunday morning after an RCMP tactical unit had to arrest activists.

The protest lasted a full 24 hours and began when 19 Greenpeace activists broke onto the site of Shell's Scotford upgrader in Fort Saskatchewan just before 5 a.m. Saturday.

Three protesters were arrested shortly after, but the remaining 16 from Canada, France, Brazil and Australia were able to scale an under construction smokestack in order to lock down the structures.

Greenpeace has said this will not be their last oilsands protest.

"You are definitely going to see a very active campaign until we get our world leaders to listen," said Mike Hudema, Greenpeace spokesperson.

Along with Lindsay's promised crackdown, comes safety concerns after some protesters were able to break into secure and potentially dangerous sites.

Shell, along with other oil companies are now reviewing its security to try to prevent another incident.

"We'll be looking at the recent situation, looking for any possible areas where there might be an opportunity to improve," said Suncor spokesperson Sneh Seetal.

But despite the promised threat of punishment, some protesters insist they will continue to do whatever is necessary to get their message across.

"For me, I'll continue to participate in non-violent direct action for as long as I feel that these issues are not being challenged," said Logan McIntosh.

Greenpeace said the protests are meant to raise awareness about pollution from oilsands development in Alberta.

Sixteen people were arrested and have been charged with mischief and breaking and entering. All of the accused are scheduled to appear in court in Edmonton on November 4.

This marks the third protest in recent weeks.

With files from CTV's Bill Fortier