LONDON, March 25 (Reuters) - Climate activist shareholder group Follow This, together with a group of European investors with $1 trillion under management, said on Wednesday they have given BP until April 1 to include their resolution in the agenda for the oil major's shareholder meeting or they will take the firm to court.

* The group demanded BP disclose longer-term strategiesunder scenarios of declining oil and gas demand, but BP did notinclude the resolution in its notice of meeting. * Follow This said it has instructed law firm Mishcon deReya to send a formal letter to BP, giving the company one weekto include its resolution on the agenda at its annual generalmeeting. * In the letter, seen by Reuters, the law firm said: "Shouldthe board now still fail to do so, our client will be left withno option but to seek the assistance of the courts to order theboard to comply with its legal obligations." * BP's AGM is scheduled for April 23. * Follow This has filed a similar resolution for Shell's AGMscheduled for May 19. Shell has not published its agenda for themeeting yet. * Typically, it is much easier for shareholders in Europe toget resolutions on AGM agendas than in the U.S. * "This case is bigger than one resolution at one company,"said Follow This founder Mark van Baal. "Shareholder democracyin the UK is at stake. If BP can block a valid resolutionwithout explanation, any company can. We will not let thatstand." * A BP spokesperson said: "The board, having taken legaladvice, concluded that the proposal from Follow This was notvalid as it would be ineffective as a direction by shareholdersto the board were it to pass at the AGM. The board is clear thatall legally valid resolutions which are properly requisitionedwill be put to shareholders."

(Reporting by Shadia Nasralla. Editing by Mark Potter)

By Shadia Nasralla