Three Afghans hurt in a twin bombing in the country's main eastern city died overnight, an official said Thursday, bringing to four the toll from an attack that heightened insecurity ahead of elections.

Meanwhile, the United Nations (search) said an Australian journalist who had been missing for several days in southern Afghanistan had returned safely to the capital, Kabul.

Two bombs hidden in crates of vegetables exploded within minutes of each other on Wednesday in downtown Jalalabad, 80 miles east of the capital, Kabul (search).

One man among the 27 injured, who included five children and five police officers, died Wednesday evening.

Faizan, a spokesman for the governor of Nangarhar (search), which surrounds Jalalabad (search), said three more men died overnight. It was unclear if they were police or civilians.

"They had all been seriously injured," Faizan, who uses only one name, told The Associated Press by telephone. "The other patients will be OK."

Officials quickly blamed the "enemies of the Afghan nation" — a byword for anti-government militants including the rebels of the ousted Taliban regime.

But a purported spokesman for the Taliban denied involvement and pointed instead to deadly feuding between rival tribes and factions in the province.

Faizan said no one had been arrested.

Nangarhar has seen a spate of bombings and rocket attacks, including a blast last week that killed two election workers in Jalalabad and a roadside bomb on Wednesday that narrowly missed another electoral vehicle.

Australian journalist Carmela Baranowska, whose employers had feared she might be kidnapped after she did not check in for several days, spoke briefly by telephone Thursday with her mother. U.N. spokesman Manoel de Almeida e Silva said she had returned to Kabul.