Evarist Bartolo warned the PL leadership on Wednesday that people from within the party who were only interested in personal gain were Labour's worst enemies.

"In its 103 years of existence, the party has always dealt with forces that are out to destroy it and which would do anything to destroy it," the former senior minister told Facebook followers.

"But the biggest damage to the PL was always done by those within it who used the party for their own personal interests - to fatten their pockets."

Bartolo's comments come hours after ex-PM Joseph Muscat, former OPM chief-of-staff Keith Schembri and former minister Konrad Mizzi pleaded not guilty to bribery, corruption and other crimes. The three were among 14 individuals and nine companies charged during a historic court hearing on Tuesday.

Throughout the day, hundreds spent hours outside the court building to show support for the former PL PM.

Another 14 individuals, two companies and a legal firm - including former minister Chris Fearne and Central Bank Governor Edward Scicluna - are being charged in court on Wednesday.

Joseph Muscat supporters outside court on Tuesday. Photo: Matthew Mirabelli

Party losing support of people with post-secondary education

On Wednesday morning, the former education and foreign affairs minister said the PL was being pulled in different directions by different people, just like a ship caught in a storm.

He warned of a lack of strong leadership that would otherwise set the party on a new route for the good of the country and the party.

Bartolo said that while the party will manage to secure more votes than the PN in the upcoming elections, it has "serious long-term problems" because of a growing gap between the party and parts of society.

While the party still had the support of those on low income and who had primary and secondary level education, it was "losing the support of those earning a monthly €2,000 and more and who have post-secondary and tertiary education".

"This is not a good sign. A party that wants to represent the state and the government, cannot have a tribal culture representing only part of the population."

PL lost elections because of enemies within

"The PL has often faced outside enemies: the British colonial government, a conservative Church and the local social class that believes it has the divine right to eternal rule.

"When the party did not have internal enemies, the PL managed to come out victorious against the external enemy.

"It lost elections when it lost wide support because of internal enemies that used the party for their own gain," he warned.

Bartolo urged the party to stop the loss of support by addressing the "serious problems created by enemies within: not just when it comes to political leadership and corruption, but also when it comes to the huge economic growth that brought about wealth and job opportunities but also burdened local infrastructure".