Euronet (EEFT - Get Report) made a $1.65 billion offer for MoneyGram International (MGI - Get Report) but said it was rejected by the money-transfer company.

Euronet, a Kansas-based maker of automated teller machines, said it made an all-stock offer for MoneyGram valued at $20 a share on Dec. 4. That represents a 43% premium to the stock's price that day and a 34% premium over the shares' close on Wednesday.

Shares of MoneyGram were surging $4.60, or 31%, to $19.50 in premarket trading Thursday.

MoneyGram rebuffed the merger proposal and declined to discuss the deal with Euronet, according to a letter to MoneyGram's board made public Thursday by Euronet.

Euronet said in the letter that a merger would combine two complementary businesses and expand the geographic network of both companies.

The deal calls for a fixed exchange ratio of 0.6179 shares of Euronet for each MoneyGram share; this would give MoneyGram shareholders a 46% stake in the combined company.

Euronet is seeking to enter a confidentiality agreement to conduct due diligence and said it would be prepared to increase its offer if the review warrants it.