Pakistan pace great Waqar Younis said the ICC should consider using only one brand of ball in Test cricket as fast bowlers find it difficult to adjust while playing in different conditions across the world.
The Pakistan cricket team played with the Dukes ball during their recent tour of England, where the visitors lost 0-2 a three-Test series.
"I have been a big advocate of the Dukes ball for many years but I feel that only one brand of ball should be used around the world for Test cricket," Younis wrote in a column for the Pakistan Cricket Board.
"It doesn't matter which brand but the ICC should make that decision. It's hard for bowlers to adjust to using different types of ball when they play around the world."
Besides Dukes, Kookaburra and SG are the other two cricket balls mainly used in international matches. While India uses SG, England, Ireland and the West Indies use Dukes and all other countries use Kookaburra.
The ICC has banned the use of saliva to shine the ball in the wake of the COVID-19 pandemic.
Younis said it wasn't an issue in England due to the weather conditions.
"One of the challenges that both teams faced in the recent Test series was the ban on the use of saliva to shine the ball. I don't think it was actually a major issue given the weather (in England).
"The pitches themselves were very dry but there was always moisture in the air and the outfields were lush so keeping the ball in good condition was not a problem. In other parts of the world, it is always more challenging to keep the ball in good condition."
Younis, who is also Pakistan's bowling coach, rued that the national team lacks experienced pacers.
"Fast bowling is the trademark of Pakistan cricket. There have been so many great ones over the years and I am confident that the future will be bright again, with a number of bowlers able to register 150 clicks on the speed gun," he said.
"We are fortunate to have some really talented young fast bowlers, but unfortunately, we don't have so many experienced ones to lead them out in the middle. It will take some time before we are back on the right track.
"Every country has a little dip at times in terms of player development and you have to go through those periods before someone emerges to become a great of the game."
The 48-year-old, who has taken 373 Test and 416 ODI wickets in his career, said fast bowlers need to focus on four-day cricket to succeed in Tests and the upcoming domestic season will be important for the development of pacers in his country.
"I want Test cricket to be a real focus for these guys and that means also placing an emphasis on four-day cricket. If you want to succeed in Test cricket it's important to play more first-class cricket to get your body used to bowling long spells," he wrote.
"The upcoming domestic season in Pakistan, with our new six-team structure, will be important for the development of our pace bowlers. But I would also like to see them playing around the world, whether in Australia or on the English county circuit."
He urged the country's upcoming bowlers to work on their fitness.
"It is not just the skills of fast bowling that our young guys need to work on. Fitness is also crucial for them," Younis said.
"As a squad, our fitness has been improving all the time but I think we are still a touch behind many other teams in the world.
"Fast bowlers in Test cricket have to be super fit to survive those long spells when the team needs you, even at the times you may not want to."
Younis said patience is the key and he has a lot of faith in the current crop of bowlers.
"Fast bowling is hard work and it cannot be learned overnight. We all need to be patient with these guys," he said.
"They have the hunger, attitude and desire and I have got full confidence that they are the future of Pakistan cricket if they carry on the hard work. Continue getting fitter and the skills will blossom."