Al Qaeda's North African wing posted on an Islamist website Tuesday photographs of five Europeans kidnapped in Mali last month and attacked Mali over its military cooperation with France.

Al Qaeda in the Islamic Maghreb (AQIM) last week claimed responsibility for the kidnapping of the five, two Frenchmen -- whom it described as French spies -- on one occasion and three other people from an undisclosed European country in a separate incident in the north of Mali a few days later.

In the two images, the hostages are surrounded by masked men holding guns. In one, the Frenchmen appear to have their hands tied behind their backs; the three others have their hands on their knees in a second. They all appear to be in good health.

Mali security forces said Monday they had arrested four people suspected of kidnapping the two Frenchmen on behalf of AQIM.

Mali is under growing international pressure to step up the fight against al Qaeda, which is plying a lucrative trade in the ransoming of Westerners kidnapped in the Sahel region.

The two Frenchmen, described by Malian officials as an engineer and a technician who work for a local cement firm, were kidnapped on the night of November 23 in the town of Hombori, about 200 km (125 miles) west of the northern city of Gao.

The statement said the Frenchmen were seized on November 24 and the three others from Timbuktu on November 25. It attacked the Mali government for its cooperation with France against Islamists, citing French usage of an airbase.

Repeated attacks on Mujahideen (Islamist fighters) to please America and France is a mistaken and unjust policy that contradicts Islamic sharia law as well as reason and will not pass without retribution, it said.

Governments in the Sahel region including Mauritania, Algeria, Mali and Niger are struggling to contain the growing threat by Islamist militants in the region, which has long been a safe haven for rebels and smugglers.

(Reporting by Ali Al-Daly; writing by Andrew Hammond; editing by Tim Pearce)