June has been the worst month in over a year for the issuance of UN-backed carbon offsets, data compiled by Reuters showed, as auditor suspensions, bottlenecks and possible rule changes hinder requests from projects. Only 3.4 million offsets were issued by the UN's climate change secretariat in June, the lowest level since May 2009, when 2.3 million were handed to clean energy projects registered under the Clean Development Mechanism. In the 12 months before June, the monthly average was 10.8 million. The April-June quarter also has been the poorest in 10 quarters with 23.9 million CERs issued since March, the data showed. Under the Kyoto Protocol CDM scheme, firms can invest in greenhouse gas cuts in emerging countries such as China or India and in return get offsets called Certified Emissions Reductions (CERs), which can be used toward emissions targets or sold for profit. Four firms that had verified the emissions cuts of three quarters of the projects registered under the CDM so far have been temporarily suspended in the past two years, including two in March, for breaching rules. This has meant that backlogs of approved projects requesting CERs and new projects seeking approval have built up, leading to fewer CERs coming to market and fuelling a near complete backwardation in the CER futures price curve. The UN's website showed a queue of over 240 projects, the oldest submission dating back to late March, which were waiting to start a process the site says is meant to take seven days. After the completeness check, projects are sent for additional information checks, which are meant to take a further 23 days before being moved to the four-week 'request for issuance' process.