Madrid, Spain (CNN) -- Al Qaeda in the Islamic Maghreb (AQIM) said three Spanish aid workers it kidnapped last month are in "good health," and Spain's Foreign Ministry said Thursday it considers the claim credible.
The three were kidnapped on November 29 in Mauritania. Last Tuesday, AQIM released an audio recording claiming responsibility for holding them, which Spain's Foreign Minister said was credible.
On Wednesday, AQIM released a second portion of the same message, a Foreign Ministry spokesman said, and in it the group says the three Spanish hostages are in good health.
The AQIM message on Wednesday added the three were being treated in accordance with Islamic law, and vowed to free "our detainees from your jails."
But the Foreign Ministry spokesman, who by custom is not identified, said the Spanish government has received no direct contact from AQIM with any demands, and added that the government would not publicly discuss details of al Qaeda's message.
Spain is holding dozens of Islamic militant convicts or suspects, including 14 sentenced for their roles in the Madrid train bombings in 2004 that killed 191 people. Numerous others are on trial or awaiting trial.
The aid workers -- two men and a woman from the Barcelona Solidarity Action humanitarian organization -- were kidnapped from a 13-vehicle aid convoy. The Spanish government soon after said it suspected al Qaeda.
On Wednesday, colleagues of the trio returned to Barcelona from their aid mission in Africa.
One colleague, Antoni Camps, told reporters at Barcelona's airport, "For us, it's very hard. We get to see our families, but what's really important is that there are three people who weren't able to come, and for their families, this is a very sensitive and tough time."
The al Qaeda message stated that two mujahedeen cells abducted the three Spaniards about 170 kilometers (105 miles) north of Mauritania's capital Nouakchott, near Nouadhibou, and in a separate incident, a Frenchman in neighboring Mali, to the east.
The Spanish government has enlisted the aid of the governments in Mauritania and Mali to help free the hostages, and Spain sent aircraft for that effort.
The three Spanish aid workers were in a vehicle toward the end of the convoy, which became separated from the rest.
Their colleagues soon noticed their absence and went back to find the vehicle, which was empty, with the doors open, and with tracks from another vehicle leading away into the desert, Spanish officials said.