Colonel Gulmurod Khalimov, the US-trained former head of Tajikistan's special police force, who defected to join the Islamic State in 2015, has been raised to the rank of Minister of War within the militant group.

Reports in the local press claimed Khalimov, known as The Tajik in Isis circles, had been promoted to replace Abu Omar al-Shishani, also known as the "Ginger Jihadi". Shishani, who was originally from Georgia and fought in Chechnya, was killed in a US airstrike in July.

The partisan news website Iraqi News claimed Isis had not officially announced Khalimov's promotion for fears he would be targeted by future coalition strikes, citing an unnamed security sources.

The United States has said it believes Khalimov to be one of the Islamic State's most senior leaders and is offering a reward of up to $3m (£2.2m) for information leading to the his location or his arrest.

He defected publically to the terror group in May 2015 pledging his allegiance to Abu Bakr al-Baghdadi in Mosul in a YouTube video.

Khalimov, 41, is considered to be a particular threat due to his counter-terrorism training, which included "crisis response, hostage negotiation and tactical leadership", the US State Department said at the end of August.

In the past the jihadi leader and trained sniper has called for public acts of violence against the US, Russia and Tajikistan. "Listen, you American pigs, I've been three times to America, and I saw how you train fighters to kill Muslims," he stated previously. "God willing, I will come with this weapon to your cities, your homes, and we will kill you."

Reuters reported Tajikistan's security services are investigating possible terror threats inside the country linked to Khalimov. The former colonel who received training in both the US and Russia has apparently been sending messages to militants Islamist and drug runners in the central Asian nation.

There are fears Tajikistan could be infiltrated by radical Islamist groups over its porous border with Afghanistan, particularly in the wake of a failed coup staged by then deputy defence minister, General Abdukhalim Nazarzoda just over one year ago.