Fitch upgraded its foreign and local issuer default rating of Cemex to B+ from B, the ratings agency said in a report.

The upgrade is based on Cemex's improved capital structure and "the gradual improvement in the US cement market and an improving outlook for the growth in the company's EBITDA and cash flow," Fitch said.

Fitch's action also takes into account the "improved confidence of the capital markets," as a result of Cemex's debt refinancing and the IPO of its Latin America subsidiary Cemex Latam Holdings, last year.

Cemex's national scale rating was also upgraded to BBB-(mex) from BB-(mex). All Cemex ratings retain a stable outlook.

Mexican industrial conglomerate Elementia, part owned by billionaire Carlos Slim, said on Wednesday it completed its agreement to combine its cement company, Cementos Fortaleza, with French company Lafarge in Mexico.