ANKARA, Turkey (AP) — Authorities in Istanbul have banned a protest rally and march by the same trade union and civic society groups who lost friends and colleagues in Turkey's bloodiest terror attack.

Dogan news agency video footage on Tuesday showed police pushing back dozens of demonstrators trying to reach the rally to commemorate the 97 victims of the twin suicide bombings. Some demonstrators were detained.

A woman demonstrator was heard shouting: "Our brothers were killed! What are you doing?"

The Istanbul governor banned the protest citing "sensitivities at this time" and the fact that the routes demonstrators planned to march along were heavily used by the public.

The bombings increased political uncertainty ahead of Turkey's Nov. 1 election and raised fears that the country may be heading toward a period of instability.