Four-time world champion Mark Selby has backed Shaun Murphy's call for amateurs to be barred from professional snooker tournaments.

An angry Murphy spoke out after a shock 6-5 defeat by 19-year-old Chinese amateur Si Jiahui in the first round of the UK Championship. 

The World Snooker Tour, however, said they "strongly disagree" with Murphy's comments adding Si, although an amateur, deserved a place based on his results.

But Selby, speaking after a 6-2 win over Ross Muir, told the BBC, "I think a lot of players agree with him. Because he [Murphy] said it after he lost, people probably think it is sour grapes and he wouldn't have said it if he had won - but I totally stand by everything he said.

"There's a reason there is a Q [qualifying] school to try to get on [the professional tour], and if you don't get on, you should have to wait another year and play in the amateur events."

Earlier the 39-year-old Murphy, who won the UK crown - snooker's second-most important title - in 2008, said, "I am going to sound like a grumpy old man but that young man shouldn't be in the tournament."

Si dropped off the main tour at the end of last season and entered the 128-man tournament in York as an amateur top-up in the field.

"This our livelihood," said Murphy, the 2005 world champion.

"He played like a man who does not have a care in the world, because he does not have a care in the world. I am not picking on him as a young man, he deserved his victory. 

"Amateurs should not be allowed in professional ­tournaments, the end," he added.

Reigning UK champion Neil Robertson, who faces amateur John Astley on Thursday, also backed Murphy.

"They [amateur players] are basically on a free hit at a pro, so I completely agree with what Shaun's saying there, because it is very dangerous," said the Australian.

In other matches, China's Ding Junhui made a break of 129 on his way to a 6-2 win over compatriot Zhang Anda, while Thailand's Thepchaiya Un-Nooh complied five century breaks as he overwhelmed seven-time former world champion Stephen Hendry 6-1.