Total SA was warned in early 2010 that its U.S. shale-gas investments could be at risk because its sales of refined petroleum to Iran ran counter to U.S. efforts to isolate the nation, according to diplomatic cables released by Wikileaks.

Dow Jones Newswires' Siobhan Hughes reportedon the warning, which was delivered by House Foreign Affairs Committee Staff in January just after Total announced a $2.25 billion investment in U.S. shale.

In...