COLOMBO (Reuters) - The world's six largest tea-growing nations have formed an international organisation to promote and develop the commodity and ensure its production is sustainable, officials said on Wednesday.India, Kenya, Indonesia, Malawi, Rwanda and Sri Lanka, which together account for more than 80 percent of black tea output, formed the International Tea Producers Forum (ITPF) at a meeting in Colombo."We hope to look at the common interest," said Mahinda Samarasinghe, the plantation industries minister for Sri Lanka, the first secretariat for the group."Definitely price stability is something important, and this will be one of the items on the table. There will be of course other objectives that would result in not only benefit to producer countries but also to consumers, such as maintaining quality standards."Top officials from the six countries signed a joint communique and agreed to establish the executive committee in November this year.The founding nations, which produce about 1.9 billion kg of tea per year, face similar challenges such as labour shortages, climate change and a need to improve agricultural practices.The forum will discuss strategies for such industry issues, Samarasinghe said.