DAKAR, Senegal — Presidential and legislative elections planned for November in the tiny, coup-prone West African nation of Guinea-Bissau can't be seen as free and fair unless progress is made on investigations of recent high-profile political killings, a senior U.N. official said.

Ivan Simonovic, the U.N.'s assistant secretary-general for human rights, made his remarks in an interview Wednesday during the international body's first high-level human rights mission to Guinea-Bissau, which has been trapped in a cycle of instability since gaining independence from Portugal in 1974.

The most recent coup occurred in April 2012, when the army arrested former Prime Minister Carlos Gomes Junior just weeks before a runoff presidential election he was expected to win. The country is currently run by a transitional administration headed by President Manuel Serifo Nhamadjo, who late last month announced new elections would be held Nov. 24.

Rights groups have long called for progress on political killings dating back to 2009, including the assassination that year of then-President Joao Bernardo Vieira.

In a telephone interview with The Associated Press, Simonovic said continued impunity for the killings would send "a disastrous message" heading into a potentially fraught election season.

He said that in meetings with Guinea-Bissau's justice minister and civilian and military prosecutors, he stressed the investigations would be a priority for the international community, which in recent months has taken steps toward deeper engagement with the country.

"It has been clearly stated that it is important for the international perception of the elections and whether they are free and fair," Simonovic said. "And of course if they are not considered free and fair by the international community then that has some very practical consequences."

The April coup led to a funding freeze from donors including the World Bank. However, during a visit to the country last month, World Bank Country Director Vera Songwe said full re-engagement with Guinea-Bissau could occur late this year or early next year.

Without aid, the transitional authorities have been unable to provide basic services like health care and education, Simonovic said. He described a visit this week to a hospital in Bissau where he said multiple children with different diseases were crammed onto the same hospital bed, and where other patients were denied treatment because of a lack of medicine.

Political violence continued after last year's coup, according to Amnesty International. Last October, authorities said a group of soldiers and civilians attempted a counter-coup by attacking a military base on the outskirts of Bissau, the capital. Amnesty said the military committed grave human rights abuses in responding to the incident, citing reports indicating six people were extrajudicially executed.

Simonovic said he had been given assurances there would be progress on investigations of political killings before the November vote. Though some investigations are ongoing, he said he had seen no evidence of "palpable" progress so far. A government spokesman couldn't immediately be reached for comment Wednesday.

Amnesty has also accused transitional authorities of censoring and threatening journalists, and banning demonstrations, measures Simonovic said would need to be corrected before November's vote.

Guinea-Bissau has long been a transit point for South American cocaine bound for Europe, and Simonovic said any strategy to combat political violence would need to address the drug trade and related corruption.

In April, the U.S. indicted armed forces chief Antonio Indjai in a conspiracy to distribute cocaine and aid Colombia's FARC rebels. The indictment was unsealed two weeks after a former navy chief was brought to New York for trial following his arrest at sea by federal drug agents.