A spokesman for Ukraine's Security Council said the army was not responsible for any explosions on Monday in the centre of the eastern city of Donetsk, where rebels earlier reported Ukrainian tanks trying to cross the city limits, according to Reuters. "There is work on clearing approaches to the city, on destroying checkpoints of the terrorists. If there are explosions in the middle of the city - then it is not Ukrainian soldiers," Andriy Lysenko told a news conference. "We have strict orders not to use air strikes and artillery in the city. If there is fighting in the city, we have information that there is a small self-organised group who are fighting with the terrorists."