The clash between a campaigning not-for-profit and BP could escalate this week if the energy giant continues to exclude a shareholder proposal at its AGM asking for an explanation of how the company will deal with a decline in long-term demand for oil and gas.

Reuters says the not-for-profit Follow This has sent a second letter to BP, saying it has until 1 April to include the proposal in the 23 April AGM papers or it may take legal action. Follow This first warned it could take legal action in mid March.

Follow This chief executive Mark van Baal, says: “This case is bigger than one resolution at one company,” according to Reuters.

“Shareholder democracy in the UK is at stake. If BP can block a valid resolution without explanation, any company can. We will not let that stand.”

BP said the resolution was blocked after taking legal advice that concluded the proposal was not valid because, were it to pass a vote, it “would be ineffective as a direction by shareholders to the board”.

“The board is clear that all legally valid resolutions which are properly requisitioned will be put to shareholders.”

At issue in the BP/Follow This clash is a proposal lodged in January, asking BP to explain to how it would “protect shareholder value” in a scenario where demand for oil and gas was declining.

The proposal was supported by other investors but was excluded from AGM papers. Follow This lodged a similar proposal with Shell.

The Financial Times speculates that the BP decision may be the first exclusion of its kind.

The issue raises question about which resolutions are permissible at an AGM, amid heightened concerns about sustainability and the climate transition.

Clashes over resolutions have become a transatlantic issue. In the US, not-for-profit As You Sow launched a lawsuit against insurance company Chubb, following refusal to accept a shareholder proposal which called on the board to publish a report assessing the risk from climate-related insurance claims.

Danielle Fugere, president and chief counsel of As You Sow, said the issue involved the “right of a company’s shareholders to have their voices heard on matters of great significance to long-term corporate strategy”.

Preparation and response to the climate are critical and campaign groups have identified it as a potential vulnerability they can campaign on during proxy seasons. These events involve some high-profile companies. They are unlikely to be the last.