Updated

Two Chechen women suspected of blowing up Russian passenger jets last month were briefly detained by police before the flights but bribed at least one airline employee to get on the planes, media reports said Wednesday.

One of the alleged homicide bombers used an intermediary to pay $34 to a Sibir airlines (search) employee to board a jet, even though she had a ticket for a flight the next day, the Interfax news agency quoted Russia's Prosecutor General Vladimir Ustinov as saying.

She got on the plane two minutes before check-in closed, he said.

The same intermediary also took a bribe from the other alleged suicide bomber to get on a Volga-Aviaexpress (search) flight, he said.

Ustinov said both the intermediary and the Sibir airline employee have been arrested.

The two planes crashed almost simultaneously on the night of Aug. 24 after taking off from Moscow's Domodyedovo airport (search), killing 90 people.

Russian Transport Minister Igor Levitin said laboratory tests of the wreckage of the Sibir Tu-154 and the Volga-Aviaexpress Tu-134 confirmed the explosions that brought down the two planes both occurred in passenger cabins, reinforcing the suspicion that the two Chechen women were homicide bombers.

He said explosive residue and information from the planes' flight data recorders pointed to an explosion in the main cabin.

The women arrived at the airport the evening of Aug. 24, accompanied by two other Chechens, Ustinov told Interfax.

"Police officers spotted them, confiscated their passports and handed them over to a police captain responsible for anti-terrorism operations to examine their belongings," he was quoted as saying. "The captain let them go without any check, and they started to try to obtain tickets in the same buildings."

It is not unusual for Chechens to be stopped by police in Moscow for questioning.

One of the women had purchased a ticket for a flight scheduled the next day but — after paying the bribe — got on the earlier flight two minutes before check-in closed, Ustinov said.

The crashes were the first in a series of recent attacks that have killed more than 430 people. On Aug. 31, a homicide bomber — said to be the sister of one of the plane bombers — detonated explosives at a Moscow subway station, killing 10.

The next day, dozens of heavily armed militants took more than 1,200 hostages at a school in southern Russia, which led to the deaths of more than 330 people, many of them children.

Female suicide bombers have become increasingly common in Russia, where they are known as "black widows" — women who turn to violence after losing husbands or male relatives in Chechen fighting.

Russia's Rossiyskaya Gazeta reported Wednesday that Russian security services have been searching for about 20 women allegedly recently trained by extremist Islamist underground cells to commit suicide terrorist attacks.