SOUTH PORTLAND — The City Council overwhelmingly approved a first reading Wednesday night of a controversial proposal that would block tar sands oil from coming into the city.

The council voted 6-1 shortly after 11 p.m. in the South Portland Community Center gym, where nearly 500 citizens, energy company workers and others had gathered to show their support or opposition.

Councilors who supported the proposal called it a compromise alternative to the Waterfront Protection Ordinance that was narrowly defeated last November, saying the new proposal would protect existing jobs and industry.

“I don’t want tar sands in South Portland. It scares me,” said Councilor Linda Cohen, who voted for the proposal along with Patricia Smith, Melissa Linscott, Tom Blake, Maxine Beecher and Mayor Jerry Jalbert.

Councilor Michael Pock offered the sole vote in opposition.

“We had an election and we won,” Pock said. “I’m sorry I’m so angry, but I do not intend to vote for this ordinance.”

The proposal now goes to the Planning Board, which is scheduled to review and take an advisory vote on July 15, to be followed by a final council vote on July 21.

The council had rescheduled Wednesday’s meeting from Monday evening, when more than 200 people showed up at City Hall, far outstripping the council chamber’s 100-person fire-safety limit.

More than 60 people offered testimony Wednesday night.

As they did at past meetings, many supporters of the proposal wore light blue “clear skies” T-shirts, while many opponents wore red T-shirts with an American flag that tout “American Energy” and “SoPo Jobs.” The turnout appeared to be about 200 in light blue T-shirts and about 100 in red T-shirts.

Some speakers called the proposal well-crafted protection for future generations from pollution that might be generated by shipping tar sands oil, while others said it jeopardizes future jobs and undermines the narrow defeat of a similar referendum last November.

Fort Road resident Deb Sandler thanked councilors on behalf of sea creatures in Casco Bay and the children of Greater Portland.

“Thank you for having the courage to stand up and vote for this new ordinance, for having the energy and patience to sit and listen to all of the concerned citizens,” Sandler said.

Jeff Leary, who lives on Mitchell Road and works for Portland Pipe Line Corp., asked councilors to consider the contribution his employer makes to the community.

“I ask that you please respect the elective process that has worked for so long in this city and do not undermine the results of the last election,” Leary said. “And please, do not unwittingly drive this city directly into the face of another legal battle that it cannot possibly win.”

The Draft Ordinance Committee’s proposal would prohibit loading crude oil, including tar sands, in bulk onto marine tank vessels and would block construction or expansion of terminals and other facilities for that purpose.

The council had appointed the committee to recommend ordinance changes after city voters narrowly rejected the so-called Waterfront Protection Ordinance last November.

That measure would have blocked the pipeline from bringing tar sands oil into the city using an underground pipeline that now carries crude from South Portland to Montreal. The defeated ordinance, which lost by 200 votes, also would have banned expansion of petroleum-related facilities on the waterfront.

In developing its follow-up proposal, the ordinance committee found that loading crude oil onto a ship could increase air pollution, and that the vapor combustion facilities needed to mitigate the problem would have a negative visual impact on the waterfront.

Tar sands, also known as oil sands, are a mixture of sand, sticky raw petroleum and water. Environmental groups involved in the “clear skies” campaign say tar sands oil is more dangerous to ship through pipelines and more difficult to clean up if spilled.

Oil industry representatives, including the Maine Energy Marketers Association, dispute those claims, saying that any restrictions are unjustified and would constrain business development, jeopardize jobs and block future crude oil shipping.

Supporters say the proposal is written to target tar sands oil from Canada, and note that it’s currently illegal to export U.S. crude oil, with some exceptions.

The proposal wouldn’t affect current uses or the handling of gasoline, diesel, biodiesel, ethanol, kerosene, No. 2 fuel oil, jet fuel, aviation gasoline, home heating oil, asphalt, distillate, waste oil, lubricants or other refined petroleum products.