MILFORD >> The rating agency Fitch upgraded Milford’s bond rating to AAA, the highest possible credit grade a city can receive, Mayor Benjamin G. Blake announced Monday.

As a result of smart financial decisions and responsible management, Milford joins an elite group of municipalities, which includes Greenwich, Darien and New Canaan in receiving the top-credit rating, Blake said in a written release.

According to Fitch, the AAA rating was based on superior financial management, healthy reserves, low debt levels, well-funded retiree costs, and a history of successful access to the municipal bond market. Fitch also commended the city for its careful management of other post-employment benefit liabilities, Blake said.

The score demonstrates the city’s fiscal health and reveals how markets see Milford’s creditworthiness. More importantly, this notable evaluation exposes the city’s strong and growing economy, he said.

Fitch’s rating recognizes that through strategic decisions and purposeful planning, Milford has cultivated its economic development and is now benefiting from a renaissance that’s unique in the state, he said.

“We’ve seen a 26 percent increase in companies moving to Milford over the past two years,” Blake said.

The new business growth has expanded the grand list and helped us deliver this year’s “historic” tax cut, which reduced taxes for all city residents and businesses, he said.

In assigning the rating credit quality, Fitch cited Milford’s strong management under Blake’s leadership and the city’s “sound financial cushion on the basis of its superior level of budgetary flexibility and history of careful financial management,” Blake said.

The agency noted Milford’s “continued solid economic and revenue growth prospects, a low long-term liability burden and strong operating performance,” Blake said.