The protesters took control of the station on Monday and began emptying oil from one of the pipelines in the nearby jungle village of Las Pozas, 110 miles north of Guatemala City. The station is owned by the French company Perenco.
The paramilitaries "are still blocking all access and have refused to allow emergency officials inside," Energy and Mines Ministry spokesman Juan Carlos Ruiz said Tuesday.
Ruiz said the seized pumping station connects oil wells in northernmost Peten province with a refining station in the port city of Santo Tomas.
Guatemala exports 25,000 barrels of oil a day, nearly all of which flow through channels now controlled by protesters, Ruiz said. The protest is costing investors as much as $50,000 a day, he said.
The government has agreed to pay ex-paramilitaries $660 each in three installments -- one this year, and two next year. But protesters want $2,500 handed over in one payment.
Former members of the paramilitary patrols have long demanded some form of payment for helping the government fight Indian guerrillas during bloody anti-insurgency campaigns that killed 200,000 Guatemalans.
But the payment plan has been criticized by human rights groups, who say the paramilitaries were responsible for many of the thousands of human rights abuses committed during the war.
Also Tuesday in Guatemala City, 40 ex-members of the presidential guard blocked the entrance of the National Palace of Culture for several hours, protesting their dismissal from the infamous security force.
They also demanded higher salaries than the $139 they receive per month in their new posts.
The guard was originally created to protect the president but allegedly grew into a squad of spies and assassins responsible for some of Guatemala's most high-profile atrocities.