The United States and the European Union have suspended some trade restrictions on Tehran.
It is the latest development in one of the world's most intractable diplomatic problems, the dismantling of Iran's nuclear programme.
The move came after the United Nations nuclear agency, the IAEA, confirmed the Iranians had started curbing uranium enrichment.
The sanctions have crippled Iran's entire energy sector, its trade and financial system.
But Malcolm Grimston of Imperial College in London said the easing of some sanctions was a first step.
"Only a small number of sanctions have been lifted, the most important ones on movement of international money, which in effect means on their export of oil and gas, are still in place and it's only for six months"
Mr Grimston said the lifting of sanctions combined with economic reforms would make Iran an attractive marketplace for international investors.
