The Akchas were among the main suspects in the attacks

The deaths of Mohammed Oulad Akcha, 28, and Rachid Oulad Akcha, 33, mean at least five of the prime suspects in the attacks died in the blast on 3 April.

The men blew up their flat in the Spanish capital as police moved in.

Spanish media said DNA tests had established the bodies were those of the Akcha brothers.

The interior ministry and the high court have not confirmed it.

The 11 March attacks, on trains in the Spanish capital, killed 192 people and injured more than 2,000.

'Killed or arrested'

Last week the interior ministry said it believed most of the culprits were either killed in the blast or had been arrested.

One body found in the rubble of the apartment in the Madrid suburb of Leganes was the suspected ringleader of the plot, Serhane ben Abdelmajid Fakhet, also known as "The Tunisian".

Another is still unidentified, but reports in Spain suggest it may be that of the sixth main suspect, Moroccan Said Berraj.

A seventh body was found to be Asri Rifaat Anouar, who was not named on international arrest warrants in connection with the attacks.

SIX MAIN SUSPECTS Sarhane ben Abdelmajid Fakhet Jamal Ahmidan Mohammed Oulad Akcha Rachid Oulad Akcha Abdennabi Kounjaa Said Berraj

Meanwhile, a Bosnian arrested on his return to Spain from his holidays has been released.

Sanel Sjekirica, 23, told a Bosnian radio station he once shared an apartment with Fakhet, but had "no other connection with him".

Eighteen people have been charged so far in the case.

Six face charges of mass murder, the others of belonging to or collaborating with a terrorist organisation.

Fourteen are Moroccan. Two are Indian, one Syrian and one Spanish.