The call follows a series of scandals that have hit the reputation of the European Union's executive body.
These include the recent Bahamas leaks which showed that former Commissioner Neelie Kroes failed to declare her directorship of an offshore firm while in her post in Brussels.
#BREAKING: #BahamasLeaks ex-EU official #Kroes implicated in latest @ICIJorg leak. It's time to end secret companies https://t.co/K6jmbpZMl2 pic.twitter.com/F6Yz8hMCVI
— Transparency Int. EU (@TI_EU) September 21, 2016
Kroes, who is now a paid adviser to Bank of America and Uber, has been called upon to explain why she kept it hidden.
The MEPs urged a tightening of the code of conduct during a debate on the business ties of past and present Commissioners with EU Economic Affairs Commissioner Pierre Moscovici.
live now #Barroso #Kroes: MEPs discuss conflicts of interests in #EPplenary @pierremoscovici — follow live: https://t.co/g0X5tKnKCy … pic.twitter.com/nMZkHBpBZ6
— EUemployees (@EUemployees) October 4, 2016
Moscovici said that the Commission wants EU citizens to know that Commissioners act "exclusively in the interests of Europe".
"Any conflict of interest therefore needs to be avoided, and there are very strict rules for this already in place. But the rules should also go hand in hand with personal responsibility," he added.
Former Commission President Jose Manuel Barroso has also found himself under the spotlight after he took up a post with investment bank Goldman Sachs this summer.
An EU staff petition calling on Barroso to give up his EU pension for bringing the institution into disrepute has received over 75,000 signatures.
The petition accuses Barosso of "morally reprehensible" behavior and says him taking the job is a "a gift horse for europhobes."
In response to the scandals, the MEPs want to see a prolonged "cooling off period" before ex-Commissioners can join the private sector. They have also proposed the Commission's Ad hoc Ethical Committee to be made independent and able to take decisions on suitable jobs for previous Commissioners.
Brussels will be keen to clean up the image of its institutions at a time when Euroscepticism is growing across the continent. Britain is set to exit the union after a referendum in June and criticism of the EU is boosting opposition parties in France and Germany.
