UPDATE 3-Petro Andina stock surges as Pluspetrol readies bid

* Bids C$8.10 cash per share

* Petro Andina stock surges 32 percent to C$9.15 (Adds response from Petro Andina)

CALGARY, Alberta, June 18 (Reuters) - Pluspetrol Resources Corp NV said on Thursday it will bid about C$400 million ($354 million) for Petro Andina Resources Inc PAR.TO to expand its oil and gas operations in Argentina, Colombia and Trinidad.

Shares in Calgary-based Petro Andina quickly surged above the offer price, closing up C$2.20, or 32 percent, at C$9.15 on the Toronto Stock Exchange, suggesting investors expect a sweeter offer.

Netherlands-based Pluspetrol, which already has extensive production in South America, said it will bid C$8.10 in cash for each share of Petro Andina,

The offer represents a 31 percent premium over the C$6.20 issue price of the target firm's recent C$27 million equity issue, Pluspetrol said.

But the market price above C$9 is a better reflection of Petro Andina's value, FirstEnergy Capital Corp analyst Martin Molyneaux said.

Petro Andina produces heavy oil in Argentina, and has exploration acreage in Colombia and in Trinidad and Tobago. In the first quarter, it produced 15,645 barrels of oil equivalent a day, a jump of 61 percent from a year earlier.

Petro Andina said in a release late Thursday that its board will evaluate the unsolicited offer and determine what actions to take in the best interest of the company and shareholders.