By Deepa Babington ATHENS (Reuters) - Thousands rallied in front of the Greek parliament on Monday to show support for Athens's place in the euro zone as leaders of the single-currency bloc gathered in Brussels to discuss the cash-strapped country's fate. The pro-euro rally, the second such demonstration in a week, came a day after an anti-austerity protest in support of Prime Minister Alexis Tsipras's hard line stance towards creditors that has pushed Greece to the brink of bankruptcy. "It's been a long time that we've been in negotiations and I feel we've been sending mixed signals to the world," said 30-year-old project manager Panagiota Kaltsa at the rally.