Irish MEPs are punching below their weight in the European Parliament, possibly due to the prevalence of independents and other factors, according to an independent organisation that analyses voting patterns.

The study by VoteWatch Europe looks at which MEPs are most successful at influencing the outcome of EU legislation through their presence on parliamentary committees and in delivering reports.

The annual survey shows that in a scale of one to five, Irish MEPs are in the second least influential cluster of national delegations in the European Parliament.

VoteWatch Europe says a possible explanation may be due to the number of independents among Irish MEPs, or the prevelance of MEPs in the far-left grouping in the chamber.

A number of Irish MEPs have challenged the findings.

A spokesman for VoteWatch Europe said: "One possible explanation is that the Irish MEPs in some of the most powerful groups of the European Parliament [the Liberal group ALDE and the centre left Socialists & Democrats group] do not have the backing of a political party.

"In the European Parliament, the independent members struggle to access key positions and reports."

The spokesman added: "Additionally, many Irish are members of the far-left GUE-NGL [United European Left-Green Nordic Left], which is often marginalized by the mainstream political groups when it comes to the assignment of important positions or reports in the European Parliament."

Of the Irish MEPs, Sinn Féin’s Liadh Ní Riada, Lynn Boylan and Matt Carthy are in the far left GUE-NGL group.

Marian Harkin is an independent in the ALDE group, while Nessa Childers, who is not running in 2019, is also an independent in the Socialists and Democrats group.

Luke "Ming" Flanagan is an independent in the GUE-NGL group, while Brian Crowley of Fianna Fáil is in the European Conservatives and Reformists (ECR) group.

Fine Gael’s Mairead McGuinness, Brian Hayes, Sean Kelly and Deirdre Clune are in the centre-right European Peoples’ Party (EPP).

The report measures the effectiveness of MEPs according to five bands, with the most influential in the first band, and the least influential in the fifth.

The most influential national delegations at the Parliament are from Germany and Italy, the second from the UK, Poland, France and Spain.

The third most influential countries include Austria, Sweden, Romania, Bulgaria, Hungary, the Czech Republic, Belgium, the Netherlands, Finland and Portugal.

The fourth group includes Ireland, Estonia, Latvia, Lithuania, Slovakia, Slovenia, Croatia, Greece and Denmark. The least influential countries are Luxembourg and Cyprus.

Fine Gael’s Mairead McGuinness is the only Irish MEP in the top 150 most influential representatives.

There are no Irish MEPs in the second most influential band (151-300).

Fine Gael’s Brian Hayes and Sean Kelly are in the third band (301-450) along with Sinn Féin’s Liadh Ní Riada and Lynn Boylan.

In the fourth most influential band are Deirdre Clune and Marian Harkin (451-600).

In the fifth are Sinn Féin’s Matt Carthy, Independents Nessa Childers and Luke "Ming" Flanagan, and Brian Crowley of Fianna Fail.

When individual MEPs are ranked according to a points system, Mairead McGuinness (FG), who is vice-president of the Parliament, has the highest score at 30 points.

Brian Hayes (FG) has 17.5 points, Sean Kelly (FG) has 16.5, Liadh Ní Riada (SF) 16, Lynn Boylan (SF) 15, and Deirdre Clune (FG) 12, and Marian Harkin (Ind) 12 points.

Matt Carthy (SF) scores 10 points, Nessa Childers (Ind) 7, Luke "Ming" Flanagan (Ind) 6.5 points and Brian Crowley (FF) 3 points.

The authors of the report say they have used a range of inputs and algorithims to assess the degree of influence MEPs exercise.

These have been gathered from EU policy experts, MEPs and others in order to provide a weighted measure of what constitutes influence.

According to the report: "This is not an assessment of the best and the worst, or the good and the bad. 'Influence' is a neutral term in this context, indicating the level of power that an MEP masters in order to get things done at this point in time.

"The study does not tell whether he/she uses that power in line with the interests of a certain segment of the public (constituents) or a stakeholder group.

"For example, an MEP may be highly influential, but have different views than those promoted by a particular group of citizens (in which case he/she cannot be their champion). Or, the other way around, an MEP may be portraying himself/herself as the champion of the interests of a particular citizens group, but in reality it lacks the needed influence to get things done in the Parliament."

Luke "Ming" Flanagan disputed the findings, describing the study as a blunt instrument.

"VoteWatch is deciding who is the most influential MEP without knowing how often they turn up in their committees, how many votes they take part in, how many speeches they make.

"Because Mairead McGuinness is vice-president [of the European Parliament] If she did absolutely nothing else under that system she’d still be graded more influential."

Mr Flanagan said he will have been a rapporteur on three parliament opinions in 2017. "That would put me in the top ten of all MEPs in the parliament on writing opinions," he told RTE News.

Mr Flanagan is a member of the European Parliament agriculture and rural development committee, and the budgetary control committee. He is also a substitute member on the environment committee.

Kieran Hartley, Fianna Fáil’s Ireland South Substitute, responded to the report by criticising the performance of Brian Crowley MEP, who currently resides in the ECR group, alongside British Conservative Party MEPs.

Mr Crowley, who ranks lowest in the list of Irish MEPs with three points, has been unable to attend Brussels and Strasbourg sessions because of ill-health.

"It is disappointing that Irish MEP's do not have much greater influence in the European Parliament, especially as we are the EU nation that will be most affected by Brexit," said Mr Hartley in a statement. "But it is difficult to have influence when we tamely gift a voice to the Tory/Unionist EP party, a party that is primarily concerned about leaving the EU.

"With an ever-increasing number of committees Ireland finds itself at a democratic deficit with the long-term absenteeism of one MEP. This is having an impact on Ireland's participation in the European parliament and in turn having an impact on Ireland's voting record."

Mr Crowley’s office responded: "Brian is currently in hospital for medical treatment and not attending Parliament at the present time. As Brian has already agreed with other journalists, he will not comment until after his release from hospital and will answer any questions at that stage."

Sinn Féin’s Matt Carthy also criticised the methodology used: "It’s basically an indication of who is most caught up in the European Parliament bubble, because it’s designed in such a way as to give points towards official positions in the Parliament, towards larger member states and larger political groupings."

Mr Carthy, who is on three European Parliament committees (agriculture and rural development, economic and monetary affairs committee, and transport and tourism) added: "If you were to care about ranking, then the biggest disadvantage is coming from Ireland, and deciding your voting pattern in Parliament on the basis of what’s in the best interests of Ireland as opposed to the larger political grouping."

However, VoteWatch suggests that some MEPs from smaller countries can tend to punch about their weight.

"Belgian and Finnish MEPs are the most influential when the average scores are considered," the report concluded.

"This means that the influence exerted by these national delegations is higher than the size of their national groups in the European Parliament would suggest. German, Romanian and Maltese MEPs are also punching above their weight."

Mairead McGuinness said all Irish MEPs "work very hard in their own committees and in plenary."

She added: "Irish MEPs are so involved in Brexit, and that's not reflected in rankings, nor should it be. There's a lot work that all politicians do that cannot be counted in rankings.

"I'm the first vice-president - it's not unusual that I would be at that level, but for me I don't look at these [surveys], I don't compare myself with others, and I don't think that's how we should work, because there's a huge amount of work we do, not just in committee and plenary, but there's a huge amount we do in Brussels, Strasbourg and Ireland."

The VoteWatch report said that British MEPs lost the most level of influence in the past year because of the Brexit vote.

Meanwhile, Luke "Ming" Flanagan has challenged the European Commission to release details of meetings and debates surrounding the future of the EU as envisaged in the Commission’s White Paper in March.

He said: "We were promised in March that there would be a full debate on the White Paper on the future of Europe. Those debates did not take place. The last [Eurobarometer] opinion poll put Ireland at 88pc in favour of the EU. If a country is 88pc in favour of the EU, what the hell are they afraid to debate the issues for? Whether you are a europhile or a eurosceptic I would imagine you would like to debate what the future of Europe is about."