Security forces shot dead at least 15 people and wounded dozens as thousands of Sudanese took to the streets on Wednesday on the deadliest day in a month of demonstrations against the military, medics said.

The protesters marched across the capital Khartoum and in the cities of Bahri and Omdurman.

Security forces fired live rounds and tear gas to prevent gatherings in all three cities, and mobile phone communications were cut, Reuters reported citing witnesses.