One of President Hugo Chavez's most threatening enemies is on the loose, and many Venezuelans wonder what new plots he has in mind.

Carlos Ortega escaped from a military prison over the weekend, and troops and police were ordered to guard ports, airports and embassies to prevent him from fleeing or seeking asylum. But those who know the 60-year-old Ortega think he might stay in hopes of reviving anti-Chavez protests before presidential elections in December.

"Carlos has always been a fighting man," Edgar Zambrano, an opposition politician who recently visited him in prison, said Monday. "I imagine if he decided to escape from prison, he's doing it to stay in the country and, while in hiding, begin a frontal fight against the regime."

CountryWatch: Venezuela

A union leader who led a crippling national strike against Chavez and later became what many consider Venezuela's most prominent political prisoner, Ortega slipped out of the Ramo Verde prison west of Caracas, where he was serving a 16-year sentence for civil rebellion. Three convicted military officers also escaped.

Prison director Gustavo Busnego said 14 guards were being interrogated, and investigators believe some may have helped the men leave the prison. He said guards reported the escape Sunday after checking one bunk and finding only pillows under the sheet, arranged to look like a dozing inmate.

Zambrano's party, Democratic Action, released a typed letter, purportedly written by Ortega from prison a week earlier. In it, he repeated a phrase he has often used: "I know that we will soon see each other again — and free."

However, he also said, "for now I am a political prisoner of a dictator who knows I am dangerous in the streets and, therefore, I prefer to stay behind bars. That is the best way of showing he fears me."

Ortega wrote that voters should boycott the presidential vote and called for street protests to "defend democracy." He signed off saying, "We will see each other soon, friends!"

Chavez has called Ortega a criminal who has conspired against democracy with Venezuela's wealthy elite.

Ortega was convicted last December of civil rebellion and instigation to commit illegal acts for his role in a 2002-2003 general strike that aimed to topple Chavez's government.

The two-month strike virtually shut down oil production in the world's No. 5 oil exporting country and cost Venezuela an estimated $7.5 billion, plunging the economy into recession. Chavez refused to step down and regained control of the oil industry by firing nearly half the work force at the state oil company.

The government also has linked Ortega, the leader of the million-member Venezuelan Workers Confederation, to an April 2002 coup that briefly ousted Chavez before street protests helped restore him to power.

Ortega has eluded authorities before. He fled arrest and sought asylum in Costa Rica, then chose to return to Venezuela in 2004, to "continue fighting this regime by any means necessary."

Ortega spent months in hiding before his arrest in March 2005 inside a Caracas bingo hall.

Some of Ortega's allies, including his lawyer, said his escape was justified because he was wrongly convicted by a biased judicial system.

But pro-Chavez union organizer Pedro Vargas called Ortega's escape "part of the opposition's Plan B" to try to destabilize the government. Attorney General Isaias Rodriguez theorized that the opposition could have "sponsored this escape."

The three military officers who disappeared with Ortega include two brothers, Col. Jesus Faria and Col. Dario Faria, and their nephew, Capt. Rafael Faria.

Jesus and Rafael Faria were serving nine-year terms for military rebellion after being linked to reputed Colombian paramilitaries detained in 2004 for allegedly plotting to assassinate Chavez. Dario Faria was arrested for theft in 2005 after a military assault rifle was found hidden in his car's fender. All three maintained they were innocent.

A daughter of Jesus Faria, 23-year-old Maria Alejandrina, said her father revealed nothing of his plan when she visited him at the prison Saturday. She said she had no idea where her relatives went, but said they'll likely "continue with their mission" — opposing Chavez's government.