* Creditors refuse to extend deadline on restructuring talks * Regional government says it is unable to help (Updates with bankruptcy request) MADRID, Feb 22 (Reuters) - Spanish engineering and renewables company Abengoa said on Monday it had decided to voluntarily request to start the bankruptcy process after its creditors refused to extend a deadline for negotiating a restructuring agreement. A proposed restructuring to tackle Abengoa’s 6 billion euro ($7.30 billion) debt mountain has unravelled since the regional government of Andalusia withdrew an offer of 20 million euros in funding as part of the overall deal. “The Board of Directors ... remains committed to seeking alternatives to avoid the non-viability of the subsidiaries that carry out the group’s activity and, thereby, preserve jobs and try to minimize the loss of value,” Abengoa said in a statement to the Spanish stock regulator.