Venezuelan crude exports to the United States declined 10 percent in September versus the previous month due to lower sales of heavy and medium grades to some of regular customers, according to Reuters trade flows data and PDVSA trade documents.

State-run oil company PDVSA and its joint ventures sent 44 crude cargoes to the United States last month carrying 724,230 barrels per day (bpd), compared with 807,065 bpd in August.

Sales of diluted crude oil (DCO) made with naphtha rose again to 348,200 bpd, from 311,130 bpd in August, but the increase was not enough to offset an export decline to regular clients including PDVSA's refining unit Citgo Petroleum, Motiva Enterprises, Phillips 66 and PBF Energy's Chalmette refinery.

PDVSA has been testing new crude blends since in 2014 it started importing light oil to use as diluent for its extra heavy output. After a supply contract with Algerian oil firm Sonatrach was terminated early this year, it has been buying Russian, Nigerian and Angolan light and medium crudes.

Even though a portion of the resulting blends was sent to the United States until August, especially to Citgo, no sale was registered in September, according to the data.

Venezuela also delivered in September a 200,000-barrel cargo of natural gasoline and a 240,000-barrel cargo of jet fuel to PetroChina Co with the United States as destination, according to PDVSA's internal imports and exports reports.

The OPEC member country imported four 500,000-barrel cargoes of heavy naphtha last month from trading firms Vitol and Trafigura and PDVSA also bought some 3.8 million barrels of Cabinda, Kissanje, Nemba and Bonny Light crudes received at its Bullenbay storage terminal in Curacao.