A United Nations official has called the situation in Guinea-Bissau tense, after the minister of justice staged a press conference to denounce threats against her life in connection with a drug investigation.  The official says threats against top officials demonstrate the power organized crime and drug traffickers already wield in the country.  Brent Latham has more from our West Africa bureau in Dakar. 

A U.N. official in the escalating fight against crime and drug trafficking in Guinea-Bissau says the situation in the country is tense after Minister of Justice Carmelita Pires staged a press conference denouncing telephone calls threatening her life. 

The official spoke on the condition of anonymity, saying he feared for his own safety and that of his family. 

He says the threats against the minister, and similar ones denounced earlier in the week by the attorney general, demonstrate the power and impunity with which organized crime factions are operating in Guinea-Bissau. 

At the press conference, Pires said she had received three phone calls overnight Wednesday.  She said anonymous callers threatened her life should an investigation over the shipment of drugs through Guinea-Bissau continue.  She said the callers told her to "keep her mouth shut," and said that "she was digging her own grave." 

The threats are linked to the investigation of two planes seized by the authorities at the Bissau airport on July 17.  One of the planes was allegedly carrying a large cargo of cocaine, which then disappeared, says reporter Lassana Cassama.

Cassama says Pires attributed the phone calls to an investigation over the fate of the supposed cargo of cocaine.  He says Pires did not speculate on who may have made the calls. 

The attorney general has said publicly that there are high ranking government and army officials that do not want the investigation to go forward.  He has accused the military of obstruction of justice for not allowing the inspection of the seized planes to proceed. 

The alleged obstruction hampered the ability of a visiting team of law enforcement officials to help local authorities, Cassama says.  He says the team was composed of officials from Interpol, the FBI, and the DEA. 

The U.N. official says no one knows where the drug cargo ended up.  The plane allegedly carrying the drugs had been under surveillance for suspicion of drug related activity, he says.  He added the seized plane has a reputation throughout West Africa for being involved in drug related operations. 

The airport control tower operator and at least four others are being held in connection with the incident.  The U.N. source says some of the detained are Venezuelans.  He says at least one of them has an outstanding international arrest warrant against him for his role in drug trafficking between Mexico and the United States. 

Guinea-Bissau and other West African nations have been struggling to contain a surge in drug trafficking through the impoverished region.  The value of cocaine shipped through Guinea-Bissau each year is estimated by the U.N. to dwarf the country's GDP, threatening to destabilize efforts at conflict prevention and development in the region.