The Prime Minister has accused the former UNC-led administration of the People's Partnership of a plot to assassinate him when he was the opposition leader.
Dr Rowley made further allegations against the now Opposition party claiming it had ties to criminals and was behind threats against Attorney General Faris Al-Rawi.
National Security Stuart Young has also accused the UNC and senior party members of having ties to gang leaders.
These allegations were made during the ruling PNM's post-budget public meeting at Piggott Corner, Belmont on Friday night.
Rowley made the disclosures, that as head of the National Security Council, he received information that on two occasions, for reasons unknown, the UNC-led government approached two hitmen to assassinate him when the PNM was in opposition.
He said since learning of this, he has to be whisked from his office and home and not allowed to mingle with the crowd at public events.
Rowley, who is the first PM to have his office at Whitehall in about a decade, said one of the first meetings he had there was with the National Security Council where he also learnt that Al-Rawi's life was under threat.
Rowley, who spoke of the alleged underworld connection that the UNC has, said, "They are desperate and because of that they are dangerous."
Young, who spoke earlier, first made the allegations that senior officials in the UNC, some of them members of Parliament, were communicating with known gang affiliates. Young said one such person "had a name that is a day of the week", referring to Akido "Sunday" Williams, who was recently charged with counselling a gang. Young said he received the "disturbing information" just before he arrived at the meeting at the corner of Erthig Road and Belmont Circular Road.
Young also claimed a senior member of the UNC executive has had conversations with members of the criminal underworld from Diego Martin, and other areas outside of an opposition-controlled constituency. The person, he said, has also had discussions with murder accused in prison on who should be UNC candidates for elections. Local government election is December 2, and the general election is due next year.
Neither the Prime Minister nor Young said if police were investigating the reports.
However, Young said crimes, such as gang activity, was one of the reasons why the police service received an additional $300 million this year. Previously, it was reported that this sum was released to the service to pay for goods and services which Police Commissioner Gary Griffith had publicly said was outstanding debt to suppliers.
Finance Minister Colm Imbert, also addressing supporters about national security, described Young and Griffith as the "dynamic duo" taking on crime. He received hearty laughter when he told the crowd that he did not want to say who he will consider to be Batman or Robin, so he will refrain from calling them that.
He chastised the previous government for not appointing a police commissioner saying the country was without one for over five years until the PNM came into power. Griffith was appointed in 2018.
Imbert said the PNM government has tackled corruption, crime and the economy and the Opposition can't deal with what has been accomplished, so they will attack him, Rowley and Young with "outrageous lies".