Maurel & Prom said on Monday its possible offer was priced at 17 pence per share for Amerisur, whose shares closed at 16.52 pence on Friday.
"M&P sees considerable benefit to shareholders from a combination and believes that the enlarged group would offer significant value upside for both Amerisur's and M&P's shareholders," the French company said in a statement.
"The combination would result in a balanced portfolio of producing assets, with a wide range of high-impact exploration and development opportunities across Latin America and Africa," added Maurel & Prom.
($1 = 0.7999 pounds)