The head of the Republic of Ireland's police force tendered his resignation to the Justice Minister, Alan Shatter, on Tuesday morning.A statement from Mr Callinan said he had decided to stand down "in the best interests of An Garda Síochána and my family".He continued: "I felt that recent developments were proving to be a distraction from the important work that is carried out by An Garda Síochána on a daily basis for the citizens of the State in an independent and impartial manner."I would like to thank the members of An Garda Síochána who I worked with during my time as Commissioner for their support and willingness to adapt for the benefit of the citizens of the State.I have great confidence that the delivery of an excellent policing service by excellent people will continue as it has done since An Garda Síochána's foundation.Martin Callinan"I wish my successor, current members of An Garda Síochána, and those due to join later this year my continuing best wishes and wholehearted support."There had been calls for the Garda Commissioner to step down over his handling of a controversy over penalty points.Mr Callinan had come under pressure to withdraw remarks about two whistleblowers made during a parliamentary watchdog hearing into alleged abuse of the points system by the force.He had described their claims as "disgusting".Padraig Mac Lochlainn of Sinn Féin said recent separate reports into the penalty points controversy by both the Comptroller and Auditor General and the Garda Inspectorate have vindicated the core allegations of the whistleblowers.He added that Martin Callinan has now made the "right decision".Mr Mac Lochlainn added: "From the moment that the allegations from the two Garda whistleblowers, Maurice McCabe and John Wilson, emerged about widespread malpractice of the penalty points issue the Garda Commissioner sought to downplay and even dismiss the allegations."Worse, he repeatedly sought to discredit the credibility of the two whistleblowers which culminated in the outrageous 'disgusting' comment at the Public Accounts Committee."Mr Callinan, who joined An Garda Síochána in 1973 and became Commissioner in 2010, said his 41 years with the force have been "challenging, enjoyable and fulfilling".He continued: "The work I carried out throughout my career could not have been done without the support of numerous men and women, and for this I would like to thank all who I have worked with during my service."It also could not have been achieved without the support of the many thousands of members of public who I have come in contact with and who I hope I have helped in some small way during my career."In a statement, the Association of Garda Chief Superintendents expressed its appreciation to Garda Commissioner Martin Callinan.It said: "In the course of a long and distinguished career in An Garda Siochana, Commissioner Callinan served the people of Ireland with commitment and dedication at all times. The Association wishes the Commissioner and his family well in his retirement."A Government statement thanked Mr Callinan for his long and dedicated service and confirmed that Deputy Commissioner Nóirín O'Sullivan has been appointed as interim Garda Commissioner. "Arrangements will be put in place for an open competition for a permanent appointment to the post of Garda Commissioner as soon as is practicable," the statement added.