Celtic midfielder Lennon made his decision to quit the Northern Ireland set-up after receiving a death threat prior to the friendly against Cyprus on Wednesday.

Armstrong claimed that the country could not afford to lose somebody of Lennon's quality because of the actions of some "mindless morons".

"I'm disappointed because he is such a good lad and hasn't deserved what has happened to him over the last 15 months," said Armstrong.

"Northern Ireland have lost a good player and I know his manager Sammy McIlroy is disappointed.

"I understand Neil's reasons because he's got a family to think about as well and he doesn't need this sort of hassle.

"He's a good player and Northern Ireland aren't blessed with that many good players that they can afford to lose somebody like Neil Lennon.

"It's a bad day from a footballing point of view.

"I'm just disappointed that some mindless morons have actually made what looks like a hoax call now, but to have the mentality to do something like that is absolutely ridiculous."

Former Northern Ireland boss Bryan Hamilton, who gave Lennon his international debut in 1994, echoed Armstrong's sentiments.

He said: "Today is a sad day and that is the shame of it all.

"I heard he might be thinking about it again and was hoping against hope that was the case.

"It is a very personal decision for Neil and a very hard one I am sure.

"I am just hoping against hope there will be second thoughts and that there will be talk and considerations.

"The real supporters of the national team will indicate they want him to be there and part of the national set-up."

Former Celtic star Frank McGarvey added: "It's a great shame because he is a good player and he wants to play for his country and he is not allowed to by fellow countryman which is terrible in this day and age.

"This is far from good for Northern Ireland which is a shame because 99.9% of the people are good.

"There are just a few who are causing this problem which is diabolical."