Tehran/Washington, July 31 (DPA) The US was 'disturbed' by reports of Iranian police and security forces breaking up a demonstration by mourners remembering those killed in recent post-election clashes, a State Department official said.

Police Thursday broke up a crowd of several hundred who had gathered around the grave of Neda Agha-Soltan, who was shot during last month's protests against the re-election of President Mahmoud Ahmadinejad. Witnesses said there were a number of arrests.

'I think it's particularly disturbing to see security forces use force to break up a graveside demonstration, to break up a group of people who are trying to exercise an important ritual under Islam, the mourning after 40 days,' US State Department spokesman Ian Kelly said Thursday.

Kelly reiterated that the US stood by 'the Iranian people who are seeking to exercise their universal right to self-expression, to demonstrate peacefully'.