(ANSA) - Rome, July 31 - Consumer group Codacons said on Tuesday that it will renew its challenge over the deal between the culture ministry and shoe king Diego Della Valle for the restoration of the Colosseum by appealing to the country's highest administrative court, the Council of State. The consumer group's announcement came after Rome Mayor Gianni Alemanno said last week that works on Rome's most famous monument were to begin on Tuesday. Codacons is questioning the legitimacy of the private-sponsorship contract, as well as the transparency of the bidding process that preceded the deal. Last week's OK by Italy's Authority for Public-Works Tenders appeared to remove the last legal hurdle obstructing the 25-million-euro contract challenged by the consumer group. Codacons filed an appeal asking for the readmission of "proposals received and deemed not suitable" and for an external commissioner to be appointed to oversee the bidding process.