FACTBOX: Key issues and numbers in WTO farm talks

(Reuters) - Talks between four of the world's big trade powers collapsed on Thursday, throwing the future of global WTO talks on free commerce into deeper crisis.

Here are some key issues and numbers in the World Trade Organization's (WTO) Doha round farm talks:

FARM SUBSIDIES - Rich countries must slash the subsidies they pay farmers, which poorer countries say distort trade. The United States has offered a $23 billion ceiling to its spending, but Brazil and others say that is more than Washington currently spends and demand a figure nearer $12 billion.

FARM TARIFFS - The European Union, which is the main target of developing country demands, has offered cuts of around 50 percent overall, but the United States had been seeking 66 percent. Brussels also wants to shelter a certain number of its most "sensitive" products from the steepest cuts.

India and other developing countries are also under pressure to open up their farm markets, but they are demanding the right to be able to shelter 20 percent of their farm sector.

INDUSTRIAL GOODS - Developed countries are demanding that developing states accept a 15 percent ceiling for industrial tariffs, while they would go down to 10 percent. But leading developing countries say this would mean they would have to cut far more than their richer trading partners.