Iran's President Hassan Rouhani has warned that opportunities provided by a nuclear deal with world powers will not last forever.

In a ceremony marking national day of nuclear energy on Thursday, Rouhani said: "The opportunity that the nuclear deal has created for us is not permanent and eternal." State TV broadcast his speech live.

Rouhani said the deal has provided opportunities for development of the country in all industrial fields, including the nuclear one.

The remarks by Rouhani appear to be a response to influential hard-line opponents who repeatedly criticize him for lack of economic results after the nuclear deal was implemented in January. Under the deal Iran accepted a cap its nuclear activities in return for the lifting of economic sanctions.