Two Saudi suspects killed when their car exploded in a mainly Shiite district of the kingdom were wanted for murdering police officers, the interior ministry said on Tuesday.
DNA testing identified Fadil al-Hamada and Mohammed al-Suwaimil, both Saudis, as the men who died on June 1 in Qatif city.
Qatif and its environs have seen criminal violence as well as protests among the Sunni-dominated kingdom's Shiite minority.
A rights group alleged that authorities "extra judicially executed" Hamada and Suwaimil, and also used "indiscriminate and excessive force" this week against civilians in the Qatif district town of Awamiya.
The ministry said Hamad, and others, were involved in the killings of 10 security forces members over the past two years in the Dammam and Qatif areas.
Suwaimil was involved in two of the killings, a ministry statement said.
Officers took "necessary action" after spotting their stolen vehicle, the ministry said at the time, without detailing how it was stopped.
"As a result, it caught fire and exploded," killing the two occupants, the ministry said.
The vehicle was found to contain weapons as well as material which exploded, the ministry said on Tuesday.
But the Berlin-based European Saudi Organisation for Human Rights (ESOHR) issued a statement accusing authorities of killing the men.
"It is the first time that the Saudi authorities have resorted to explosives to extra judicially execute people in the Eastern Province of Saudi Arabia," it said, but did not add how it believed the blast occurred.
A witness told AFP there was a "very huge" explosion.
Last month, violence escalated around a redevelopment project in the old Almosara section of Awamiya, a Qatif district town.
Three UN rights experts called on Saudi Arabia to halt demolition of the neighbourhood which, they said, reportedly caused "injury, deaths and material losses to the civilians".
The interior ministry said criminals engaged in the drug and arms trade were involved in the Almosara unrest, which earlier led to the death of a policeman and at least two civilians.
An explosion in Almosara on Sunday killed a police major, the latest victim.
Since then, security forces "have been resorting to excessive and indiscriminate force by firing directly at civilian targets in the neighbourhoods and on the streets adjacent to the Awamiya Police Station," ESOHR said on Tuesday.
One resident told AFP that many people had been wounded since Sunday night, and blamed police.