In November, the ITF launched the World Tennis Tour which came into force at the start of this year.

It serves as a "player pathway" between the junior and elite levels of the professional game.

The ITF had carried out reforms designed to help talented junior players progress to senior level, with the launch of the Tour a part of this.

A three-year review of professional and junior tennis found too many players try to compete on the professional circuit and it is difficult for junior players to come through.

In announcing changes, the ITF stated it hoped that around 750 men and a similar number of women would be classed as professional.

But the world governing body admitted the system is currently only working for the top 350 men.

Those players are catered for by the ATP Tour and ATP Challenger Tour, but below that the ATP, unlike the Women's Tennis Association (WTA), is awarding only limited ranking points for the series of $25,000 (£18,900/€22,100) tournaments.

"While the continued allocation of WTA ranking points at $25,000 tournaments provides for an estimated 650 female professional players, it has become clear in recent weeks, from player feedback and data, that there are issues regarding the men’s professional tennis circuit that need resolving," the ITF said in a statement.

"The decision of the ATP to significantly reduce its points at $25,000 tournaments in 2019 has led to fewer playing opportunities and less progression for male players.

"Only the ATP can decide how it allocates its points, but the ITF believes that restoring ATP points at $25,000 tournaments would allow for an uplift in the number of male professional players being provided for from the current 350 to an estimated 600.

"A collaborative effort is critical if we are to secure an immediate and effective solution to the issues faced in the men’s game and provide much needed certainty to players."

Kris Dent, the ITF’s senior executive director of professional tennis, told Press Association Sport the ITF had spoken to the ATP about the matter a number of times.

"To date they haven’t agreed to put those points back in," he said.

"I don’t want to speak for them but my understanding is they want to wait and see how this plays out over the first two quarters of the year but we believe the issue is more immediate than that and it would make immediate sense to have those points back in.

"At the moment we’re not addressing the player opportunity issue and creating essentially a bottleneck at the 25,000 level, which understandably is causing frustration for the players who are in that ranking band."

Fierce criticism has been aimed at the ITF for the changes made to the sport.

Among those to have expressed their disapproval is Romanian-born Canadian player Maria Patrascu, who has started a petition on Change.org entitled "Change the ITF Tennis Rules".

The petition has been signed by nearly 15,000 people.

Leading coaches such as Toni Nadal, Patrick Mouratoglou and Magnus Norman have also spoken of their worries.

Following a recent ITF Board of Directors meeting, a number of adjustments have been made to the World Tennis Tour, including another increase in qualifying to up the number of players competing each week.

It is also stated that where pre-qualifying and wild card competitions are created to offer additional playing opportunities, such events will be governed by full ITF World Tennis Tour regulations.

Additionally, player feedback will be canvassed on the potential introduction of 48 qualifying draws, with the ITF Board of Directors noting that playing twice a day without a day off risks player health issues

"The ITF World Tennis Tour is a long-term project and the ITF is committed to making appropriate changes based on player feedback and analysis of data, where it is within its authority to do so," a statement reads.

"Unquestionably, the previous structure was not fit for purpose and major change was needed to secure the long-term health and integrity of our sport.

"The ITF, ATP and WTA worked together to reform the player pathway, an approach that sought to address these issues and incorporate the clear recommendations made by the independent review panel in December 2018.

"All three bodies have a continued joint responsibility to monitor, review and make appropriate adjustments in the best interests of players, to achieve the common objective of fair opportunities and a clear pathway in professional tennis."

The latest changes follow the increase in qualifying draws from 24 to 32 players at $25,000 and $15,000 (£11,300/€13,300) levels announced last month.