They are up in arms over his comments on the border state of Johore and demanding retaliation by the Malaysian government which will discuss its stand at a cabinet meeting tomorrow.
Mr Lee is famous for telling other countries how to run their affairs, while being equally adamant that he will not tolerate foreign interference in Singapore. He sees no contradiction in this position but may have finally gone too far.
The latest row exploded when lawyers for an opposition politician, Tang Liang Hong, released an affidavit made by Mr Lee, who was suing him for libel.
In the affidavit, Mr Lee expressed surprise that Mr Tang was seeking refuge in Johore which he described as being "notorious for shootings, muggings and car-jackings". Yesterday Mr Lee said that not only did he unreservedly apologise but would seek to have the offending remarks deleted from the court record.
This description of a neighbouring state was bad enough in itself, but added to a growing feeling that Singaporeans in general, and Mr Lee in particular, were doing Malaysia down. Last year Mr Lee caused outrage when he suggested that his fellow countrymen would have to pull up their socks or they might be forced back into a federation with Malaysia - a union ended on his insistence in 1965.
Also simmering is a feeling that Singapore discriminates against its minority Malay Muslim population in favour of the majority Chinese population.
Malaysia, which supplies Singapore with its water, most of its food and a significant proportion of its labour force, is in a strong position to retaliate if it feels that Singapore is stepping out of line.
The New Straits Times, the country's leading newspaper, has called for a withdrawal of all contacts with Mr Lee and his son Lee Hsien Loong, who serves as a deputy prime minister.