Panama joins smaller nations in dropping support for policy aimed at cutting maritime emissions

US “bullying” over a proposed carbon levy on shipping appears to be paying off, experts have said, after Panama reversed its support for the measure.

In a leaked document seen by the Guardian, the key maritime state has co-sponsored a proposal to the International Maritime Organization that would in effect cancel the carbon levy and undermine attempts to cut greenhouse gas emissions.

The shipping industry accounts for about 3% of the world’s carbon output, a proportion likely to rise without a move to green technologies.

Scores of developing countries have been the target of “unprecedented” bullying from the US over the issue – behaviour that one expert has called “thuggery”.