The energy company Royal Dutch Shell and the Spanish energy company Repsol have signed a multi-billion dollar deal with Iran's state oil company to develop gas fields in the Persian gulf, but the deal may lead to sanctions from the United States. Rumors of nuclear development in Iran have led the US to discourage banks and oil companies from doing business in that country, and approval for the deal could take at least a year. Shell's 2006 profit of $23.3 billion was the largest ever by a British company, though the company also has strong roots in the Netherlands. Environmental groups have increased their efforts to get Shell to spend more of their profits on oil spill and pollution cleanup.