Pakistan, June 3 -- US Secretary of State Marco Rubio has expressed optimism that a diplomatic agreement with Iran could be reached, but stressed that Tehran must significantly scale back its nuclear programme before any sanctions relief can be considered.

Read More: Rubio says Iran response needed today

Speaking before the Senate Foreign Relations Committee on Tuesday, Rubio said negotiations remain active and could produce results in the coming days or weeks. His remarks come as the three-month conflict involving the United States, Israel and Iran remains unresolved, while the closure of the Strait of Hormuz continues to affect global energy markets.

Rubio stated that reopening the strategic waterway is a key requirement for any last...