Tehran's Imam Khomeini airport is operated by the Revolutionary Guards
Iran's Revolutionary Guards have won a $2.5bn tender to build a railway route linking the south-eastern port of Chabahar to Iran's rail network.
Transport minister Hamid Behbahani said it was part of a transit route for goods from Chabahar to the north-eastern border town of Sarakhs.
The Guards' engineering wing, Khatam-ol-Anbia, has been awarded government contracts worth billions of dollars.
These include the operation of Tehran's Imam Khomeini international airport.
Last month, more than half of Iran's national telecommunication company was ceded to a consortium partly owned by a Revolutionary Guards affiliate fund, as part of the country's privatisation of state assets.
The $8bn deal was followed by allegations that a rival consortium had been forced out of the bidding "on security grounds".
The Guards are thought to control about a third of Iran's economy through a series of subsidiaries and trusts.
The force is estimated to have 125,000 active troops. It boasts its own ground forces, navy and air force and oversees Iran's strategic weapons.