在R中的nnet multinom函数中抑制收敛消息

I am using knitr in R to produce a document of model outputs. I have suppressed messages and warnings in my code chunk. But I still get the convergence messages. I have looked for settings in the net package and in the multinom function. Does anybody know how to suppress them? I have looked on SO and on the internet. Someone asked a question in 2006 but I can't get the answer returned (and I don't know if it relevant today).I am using knitr in R to produce a document of