MADRID (Reuters) -It remains unclear whether Spain’s LNG capacity could be used to help manage any shortfall in European gas if Russia were to halt supplies, the chief executive of power and gas group Naturgy said on Friday. Spain operates six of the regasification plants needed to take delivery of liquefied natural gas and return it to a form that can be used as fuel, more than any other European country. “We (Spain) have infrastructure but we have to see whether it would be possible to get spare LNG capacity to make up for the shortfall,” Francisco Reynes said in response to a question by an…