Isis in Libya: Colonel Gaddafi's henchmen join the West to purge Isis from North Africa

Commanders who were once loyal to disposed despot Colonel Gaddafi have returned to Libya to join the West in purging Islamic State (Isis) from Sirte. Gaddafi loyalists who defended the dictator during the 2011 revolution have been recruited to battle the extremists in Muammar Gaddafi's birthplace.

The West's forces are ready to back a huge operation to expel Isis (Daesh) from the Mediterranean coast with British and American special forces already conducting intelligence-gathering operations around Sirte. The anti-IS alliance fears that IS will use the city as a springboard to launch attacks against European cities this summer.

The returning commanders see defeating IS as a chance to redeem themselves in the eyes of Libyans. Foreign secretary Phillip Hammond, while visiting the country since a new government was formed in April, pledged to help the Libyans battle the extremists.

Now different Libyan armed factions have begun encircling Sirte with a joint force consisting of officers from the UK, France, Italy, Germany and the US said to be planning to invade. Despite losing ground in Iraq and Syria, IS has been gaining ground in Libya, despite losing the key town of Derna on 21 April.

Its forces are led by former militants hardened by fighting in Syria and Iraq. According to the Telegraph, 2,000 militia from the port of Misrata are gathering at Abugrein, to the west of Sirte. Meanwhile, to the east, in the town of Ajdabiya, troops are massing under General Khalifa Heftar who fought to topple Gaddafi in 2011. Among Heftar's senior commanders is General Ali Kanna, a Tuareg fighter who fought for Gaddafi, but fled to neighbouring Niger when Tripoli's fell in August 2011.

He is understood to have been invited by Heftar and Mattia Toaldo, a Libya expert with the European Council on Foreign Relations told the Telegraph: "Some of the ex-Gaddafi era people are hoping that they can redeem themselves by joining the fight."

Sirte is said to have 6,000 IS gunmen now controlling the streets under their brutal brand of Sharia law. The roads around Sirte are littered with landmines and roadside bombs.

Heftar has 7,000 troops on his side as well as an air force and new armoured vehicles given to him by Egypt President Abdel Fattah el-Sisi, according to reports. The UK had planned to send 1,000 ground troops to Libya as part of a 6,000-strong international force, but the new government said they did not want extra foreign help.