Al-Qaida may have moved closer to a terrifying alliance with Isis.

In a message entitled "A Statement on the Crusade Alliance" posted on Twitter, al-Qaida in the Arabian Peninsula implored mujahideen to stop infighting and come together to fight common enemies.

"We recommend that all the mujahideen forget their differences and stop fighting among themselves – and instead strive to push off this crusade that has been targeting everyone."

"This campaign is indeed a campaign against Islam, against the rule of God – and its intention is to keep the Muslims the way their enemies want them to be – with no command or anything of their own.

The message continues, "We call upon ALL the Muslims to strive for the victory of their brothers against the crusade in whatever way they can – be it money or tongue."

It encourages Muslims to join forces against America.

"We also emphasize that anyone who can pound and the Americans – be it financial, military or media – must strive to do so, as they are the leaders and founders of this war."

The two jihadist groups split earlier this year, after Isis (now known as the Islamic State) refused to follow directives from al-Qaida's command to concentrate its efforts in Iraq and reduce the level of violence it uses.

In a recent interview in Fiscal Times, Hisham al-Hashimi, a former adviser to the Iraqi Security Forces and the author of a just-completed book about Islamic State, said that analysis of recent rhtoric from al-Qaida suggested that the groups may be moving closer to reconciliation.

"The attacks by the US and her allies will unite the two groups. I have been monitoring al-Qaida's leaders' rhetoric towards Baghdadi," al-Hashimi told the Fiscal Times. "They are getting softer and softer… The Islamic State, regardless of how big or small it becomes, will come back to its mother: al-Qaida."

He said that Isis had much to gain from al-Qaida's "historical roots and global networks".

Al-Qaida in the Arabian Peninsula is currently battling government forces in Yemen, and is believed to be behind a number of plots to bring down western airliners using concealed explosives.