Iran on Wednesday urged Asian companies to invest in the country, saying the lifting of nuclear-linked sanctions had opened vast opportunities, but campaigners warned firms they might end up aiding "terrorism".

Central bank governor Valiollah Seif told a business summit in Singapore that reforms put in place since President Hassan Rouhani took office in 2013 helped restore economic stability, while the lifting of sanctions had reintegrated the economy with the rest of the world.

Iran's gross domestic product is expected to grow 5.0 percent this year and next, up from 3.0 percent over the past two years, Seif told businessmen from Singapore, Malaysia, South Korea and Australia.

Tehran in January signed a historic deal with Western powers to end years of crippling sanctions in exchange for curbs on its nuclear programme, which Iran has long insisted was for peaceful purposes rather than building atomic weapons.

The United States and the European Union continue to impose penalties against Iran over its support for armed movements, ballistic missile programme and human rights record.

Iran provides financial and military support to Lebanon's Shiite militia Hezbollah and Palestinian Islamist groups, considered by some Western countries as terrorist organisations.

Advocacy group United Against Nuclear Iran cautioned foreign companies against doing business with Tehran, running a full-page advertisement in the Financial Times Asia edition Wednesday panning the summit.

"Any international company doing business in Iran could find itself inadvertently supporting terrorism -- from Hamas and Islamic Jihad to Hezbollah and the Houthis in Yemen," said Mark D. Wallace, chief executive of UANI.

But Seif said the lifting of the nuclear-linked sanctions "has created unprecedented opportunities for investors" in Iran.

Outside oil and gas, investors can also seek opportunities in petrochemicals, steel, copper mining, pharmaceuticals, telecoms, aviation, machinery, tourism, infrastructure and information and communication technology, he said.

Seif cited Iran's $450 billion economy, skilled and educated workforce, 80 million population and cheap access to energy resources among the country's advantages.

Iran has the world's biggest gas reserves and the third largest oil reserves, he said.

Hossein Yaghoobi Myab, director-general for international affairs at the Iranian central bank, said at the meeting that since the lifting of sanctions, companies from China, Japan and South Korea had visited Iran.

"We have had a lot of negotiations. Some of them have actually led into concrete agreements and compacts with the Iranian side," he told reporters.

Singapore and Iran signed an agreement to promote and protect investments in February, less than two months after the sanctions were lifted on January 16.