Since 2004, the Commission and national competition authorities have adopted over 1000 decisions, the Commission said. Between 2004 and 2014 over 85% of all decisions applying EU antitrust rules were taken by the national bodies, it said.
However, some NCAs are unable to apply EU rules independently, the Commission said
Some NCAs have insufficient human and financial resources to enforce the rules, while others do not have the tools they need to detect and tackle competition law infringements, such as the investigative powers to gather evidence stored on laptops or mobile phone, it said.
National law can also prevent NCAs imposing effective fines for breaches of EU competition law, allowing companies to restructure to escape paying fines, it said.
"These gaps and limitations in NCAs’ tools and guarantees mean that companies engaging in anti-competitive practices can face very different outcomes of proceedings depending on the member states in which they are active," the Commission said.
"A legislative proposal is therefore needed to empower the NCAs to be more effective enforcers of the EU competition rules to ensure that NCAs have the necessary guarantees of independence and resources and enforcement and fining powers," it said.
The proposed rules will provide the NCAs with a minimum common toolkit, effective enforcement powers, plus the financial and human resources and investigatory powers that they need to gather all relevant evidence, it said.
NCAs will also be able to impose "proportionate and deterrent sanctions" for breaches of the EU antitrust rules, with rules to ensure companies cannot escape fines through re-structuring.
The national bodies will be able to enforce payment of fines against companies that do not have a legal presence on their territory, "an important feature since an increasing number of companies operate internationally", the Commission said.
Coordinated leniency programmes will increase the incentives for companies to report participation in a cartel, it said.
The proposed rules are the form of a draft Directive which, once adopted by the European Parliament and Council, will require national implementation.
Commissioner in charge of competition policy Margrethe Vestager said: "EU antitrust rules make markets work better, with member states' competition authorities and the Commission working hand in hand in this regard. That is why we want all national competition authorities to be able to take decisions fully independently and have effective tools at their disposal to stop and sanction infringements. Because a well-functioning single market is to the benefit of European consumers and businesses."
The Commission said in October 2016 that European antitrust authorities would gain increased powers to prosecute breaches of competition rules.
The Commission's annual work programme set out a list of actions that the Commission planned to take in the coming 12 months, including 21 new initiatives and includes 18 proposed changes to legislation.
Included in the new initiatives, under the title 'A deeper and fairer internal market with a strengthened industrial base', was a proposal to "[empower] national competition authorities to be more effective enforcers".
Publication of the programme followed a public consultation that found that NCAs should be given more power on breaches of antitrust rules. The public consultation, launched in November 2015, asked for views on how to ensure that NCAs could act independently in enforcing competition rules, detecting and tackling infringements, imposing fines, and putting leniency programmes in place.