Gunfire and more explosions have been reported at the Toulouse siege flat where gunman Mohammed Mehar, wanted in connection with the killings of three children, a rabbi and three soldiers, has been holed up for more than a day.
As sources say the siege is reaching the end, unconfirmed reports on the BBC said that police had broken into the flat.
French interior minister Claude Gueant had earlier raised doubts that Merah, the man wanted for the Ozar Hatorah Jewish school killings and the deaths of three soldiers, was still alive. Two shots were heard by police and soldiers who have laid siege to the flat in which he is holed up.
More than 29 hours after French commandos blocked off streets and surrounded the flat of Merah in Toulouse, Gueant revealed there had been no overnight communication with the suspect.
Merah, a 23-year-old of Algerian descent said he killed seven people, including three children, in three separate attacks.
He said he acted to avenge the deaths of Palestinian children and of French military operations abroad. He told police he wanted to die "weapons in hand", Gueant added.
It is not known if Merah is still alive as there have been no signs of life for a few hours.
Guant said it was "quite strange that he did not react" to the explosions that commandos set off overnight to itnimidate him into giving himself up.
The minister added: "We have one priority: to take him alive so that he can surrender to face justice. We hope he is still alive.
"We heard two shots, we don't know what they were. Despite redoubled efforts throughout the night, there has been no contact with him."
The first blasts prompted speculation that negotiation had finished and police had launched an assault on the flat.
Ministerial sources hinted that the operation to apprehend him could last much longer than expected, however.
"[The blasts] were moves to intimidate the gunman, who seems to have changed his mind and does not want to surrender," interior ministry spokesman Pierre-Henry Brandet said.
Police sources hope Merah will be weakened by fatigue.
Merah, who says he is a member of al-Qaida, is armed with a Kalashnikov high-velocity rifle, a mini Uzi 9mm machine pistol, other handguns and possibly grenades, officials said.