MEXICO CITY (Reuters) - Billionaire Carlos Slim's conglomerate Grupo Carso (>> Grupo Carso S.A. de C.V.) on Thursday reported a higher first-quarter profit as lower sales and financing costs offset a dip in revenue.

The conglomerate's businesses, which include construction, retail, real estate and oil services among others, reported a 4.5 percent lower revenue in the January-March period compared with the year earlier.

Profit rose 21 percent to 1.689 billion pesos (76 million pounds) from 1.4 billion pesos in the year-earlier period, helped by lower debt payments and a drop in sales costs that outpaced the revenue decline.

The retail division, which includes Slim's Sanborns (>> Grupo Sanborns SAB de CV) chain of cafes and his Sears department stores among others, reported a drop in same-store sales of between 2 percent and 5.8 percent, reflecting weaker consumer spending.

Carso's industrial division reported lower revenue from all its businesses except its transformers unit and a unit that builds cables for cars.

The infrastructure and construction division also reported broadly lower revenue, except in its cable-laying and civil engineering businesses.

Slim's biggest business, phone company America Movil (>> America Movil SAB de CV), is due to report first-quarter results on Tuesday.

(Reporting by Elinor Comlay; Editing by Mohammad Zargham)