The former Westlife singers have developed a bitter rivalry because Kian, 33, was paid £40,000 more to take part in ITV's 'I'm A Celebrity...Get Me Out Of Here!' earlier this month than Nicky, 35, earned for appearing on the BBC series 'Strictly Come Dancing' last year.
A source told the Daily Star newspaper: ''They're barely speaking; they're all looking out for number one now. Nicky was angry and hurt by the difference in their pay-outs as it creates an unhealthy competition among them - he wonders why Kian is worth so much more than he is.''
The King of the Jungle took home £100,000 for his stint on reality TV, while Nicky was paid £60,000.
But Kian branded the rumours ''absolute rubbish'' on his Twitter page on Sunday (29.12.13).
The source said: ''Since the split there has been a lot of bad blood between the boys over their careers. Mark is hoping for big things next year and if it means casting a dark cloud over Shane's career then so be it.''
Westlife announced they were splitting up in 2011 and performed together for the last time in June 2012.
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