Jihadists shoot, behead 3 fighters accused of defecting to another terror group in Afghanistan

Three Islamic State fighters have been executed by jihadists after being accused of defecting to the Taliban as a brutal turf war escalates between the rival factions in Afghanistan.

The killings come days after the Taliban sent a letter to ISIS warning them to stay out of the country, saying there is room for only 'one flag, one leadership' in their fight to re-establish strict Islamist rule, Daily Mail reports.

One video posted on pro-ISIS accounts shows a line of armed fighters standing behind two kneeling men who are shot dead by one of the militants with a handgun.

In a separate execution, pictures appeared to show another alleged defector being beheaded.

It was gathered that the groups declared war on one another in April after the Afghan Taliban branded ISIS' self-declared caliphate illegitimate and refused to declare allegiance to its leader Abu Bakr al-Baghdadi.

ISIS responded by launching recruitment drives deep into Taliban territory, allowing them to expand rapidly - even reportedly replacing the Taliban as the dominant controlling force in one district.

The warning letter from the Taliban came amid heavy fighting this week in eastern Afghanistan between the Taliban and breakaway factions who now swear allegiance to Islamic State, which in the past year seized large swaths of Iraq and Syria.

The entry of Islamic State, while its numbers remain small, has complicated Afghanistan's already escalating war following the withdrawal of most foreign troops at the end of last year.

The letter addressed to Islamic State leader Abu Bakr al-Baghdadi said the Taliban 'based on religious brotherhood asks for your goodwill and doesn't want to see interference in its affairs'.

The Taliban have fought to topple Afghanistan's Western-backed government since the U.S.-sponsored military intervention that toppled their own five-year rule in 2001.