Analysts said the likelihood of a bond default was growing, after Pacific used a 30-day grace period to extend January interest payments of more than $66 million. Such an extension was agreed to in the bond contracts, but rating agencies still lowered Pacific ratings to default level. The Toronto-based company, like other energy producers, has been functioning in an environment of declining crude prices and with the refusal of state-owned Ecopetrol to renew its lease on the Rubiales oilfield.

Investment firm EIG Global Energy Partners, a subsidiary of Harbour Energy Ltd, has offered to buy all of approximately $4.1 billion in Pacific debt.

Pacific has not responded to the offer, but it said in an emailed response to queries from Reuters that it reserves the right to make payments before the period expires. "We continue to analyze all the scenarios and available options to improve our structuring of capital, including, as we have announced, renegotiation with creditors," the company wrote the email. On Thursday Pacific extended until February 26 its minimum liquidity deadline with a group of banks with which it has $1 billion in loans. Analyst Juan Felipe Pinzon of Profesionales de Bolsa brokerage said he saw little room for Pacific to fulfill its obligations this month as low oil prices affected its cash flow. "I really don't think Pacific has the money to pay even the first interest payments on its debt within 30 days, nor the debt that will come due after," Pinzon said. "Its liquidity can't keep pace." Stock analyst Luisa Diaz at Acciones y Valores brokerage said, "The situation is serious because banks won't roll over the debt, and from there it could enter default." The company's shares, once the top traded stock on the Colombian exchange, have lost 97.3 percent of their value since 2011. Analysts said that Pacific could accept EIG's offer to buy its debt, and EIG could inject cash into the company, diluting the power of current shareholders and making Pacific viable for eventual sale. Pacific has said there is "no interest in liquidating."

The government's business watchdog stepped up its monitoring after the delay in bond payments, and is meeting weekly with the company and asking almost daily for cash flow information. "These circumstances naturally have led us to have a special caution," regulatory superintendent Francisco Reyes said in an interview.

Pacific employs hundreds of oil industry companies that provide secondary services.

(Reporting by Nelson Bocanegra; Additional reporting by Julia Symmes Cobb in Bogota, Marianna Parraga in Houston and Marco Aquino in Lima; Writing by Julia Symmes Cobb)

By Nelson Bocanegra