World body FIFA has told Indian soccer to sort out its differences after a move to hand the I-League's top-tier status to the franchise-based Indian Super League (ISL) drew a threat of legal action.

FIFA said clubs needed to work with the All India Football Federation (AIFF) after the national body moved to strip the I-League winners of their place in the AFC Champions League qualifiers and give it to the ISL.

Despite an appeal from aggrieved I-League club owners, FIFA refused to intervene and said they needed to find a solution with the AIFF.

"It was clear that there are numerous aspects of the recommendations that still require further consideration prior to them being implemented," FIFA wrote in a letter to the ­I-League clubs. "We therefore strongly believe that the AIFF is best placed to do this."

The collision between the rival competitions has been coming since the ISL made its debut in 2014. The ISL, modelled on cricket's hugely successful Indian Super League, quickly overtook the I-League's viewing figures as it attracted veteran stars like Alessandro del Piero and Nicolas Anelka.

Six I-League clubs have challenged the plan to give the ISL winners India's slot in the Champions League qualifiers, an honour reserved for a country's top league.

Ranjit Bajaj, owner of I-League champions Minerva Punjab, earlier promised to launch legal action if FIFA does not step in.

"I am surprised to find FIFA turning a blind eye to the clear and obvious violation of FIFA statutes and principles by the AIFF which would not be acceptable anywhere in the world," he wrote in a letter to FIFA. "We strongly believe that the AIFF is totally incompetent in handling the crisis which is being faced by the Indian football."

But AIFF Secretary-General Kushal Das said the national body was not shutting the door on the I-League.

"We have always maintained the body which is in the best position to direct Indian football is the AIFF," Das told AFP.

"There can be suggestions from various stakeholders, but ultimately it is the AIFF who has to implement it taking into account all practical issues, and FIFA simply said that is indeed the case."