Last month, WWF-UK took out a full-page advertisement in the Financial Times alerting the financial community to BP's alleged failure to consider the social and environmental impacts of its Baku-Tbilisi-Ceyhan pipeline.
The environmental charity says that the move signals its determination to use its influence to set down expectations of how investors should apply environmental and social criteria to major project lending.
"We intend to show companies like BP that even if they won't directly talk to us over such issues, we will not give up the fight," said Robert Napier, chief executive at WWF-UK.
"If we're to protect this planet that we're currently in danger of trashing, we must change the behaviour of companies and individuals in any way we can," he said.
"We intend to use every ounce of our influence with investors who wish to be seen as ethically responsible to put pressure on companies such as BP to change their attitude to environmental protection."
The charity intends to approach individual investors to point out that their involvement in the Caucuses pipeline, which runs through Turkey, Georgia and Azerbaijan and is already half-built, undermines international environmental guidelines.
The charity says that the pipeline, which has attracted international criticism from environmental pressure groups, will plough through national parks and wetland areas and has the potential to cause a major environmental disaster.
In addition, the charity is also calling on the International Finance Corporation, the European Bank for Reconstruction and Development, and Britain's Department for International Development to uphold their own ethical standards before approving funding for such projects.
WWF-UK said it will continue to reject overtures from BP to rebuild the relationship between the charity and the petroleum giant.