When a tax warrant issued pursuant to the authority contained in section 31-266 has been returned unsatisfied either in whole or in part, and the amount collectible from the employer named therein by means of such warrant represents contributions due with respect to at least four calendar quarters, and the employer, after ten days’ notice sent to his last-known address by registered or certified mail, has failed to pay such amount in full, the administrator may bring a civil action returnable to the superior court for the judicial district of Hartford to enjoin such employer, until such amount, with interest and costs, has been paid in full, from entering into any contract of employment as a result of which he will further become liable to pay unemployment contributions.