Caerphilly County Borough Council has denied a link between a 12-month rise in fly-tipping and a cut in the opening hours of its civic amenity sites.
According to its own statistics, there were 2,461 cases of fly-tipping in the last financial year – up from 2,052 in 2014/15.
The opposition Plaid Cymru group, which submitted a request under the Freedom of Information Act for the figures, have blamed the 20% increase on the fact that opening hours at civic amenity sites were reduced in April 2015.
The cost of clearing up and disposing of the dumped items came to to more than £185,000 in 2015/16 and a total of 185 people were issued with fixed penalty notices.
Councillor Colin Mann, leader of the Plaid Cymru group, said: “It cannot be a coincidence that after opening hours were reduced the amount of fly tipping incidents increased.
“If some drivers turn up and find the civic amenity site is shut they may be tempted to find alternative places to dispose of waste. It is something I would deplore, but it may well be happening.”
However, a spokeswoman for Caerphilly County Borough Council said: “If the data for the last six years is examined, it can be seen that there is no apparent correlation between the alteration of civic amenity site opening times and the number of fly-tipping incidents.
“For example, in 2010/11 the council dealt with 2,680 incidents, in 2013/14 2,609 incidents and in 2015/16 2,586 incidents.
“It remains the responsibility of all residents to ensure their own waste is disposed of appropriately. The council has taken a number of successful prosecutions and will continue to pursue those who commit environmental crime.”
Plaid Cymru has said it will review the existing opening hours if it wins next year’s local election.
Cllr Gez Kirby, Labour group spokesman, said: “If the nationalists really believed Caerphilly Council has the resources to extend opening hours, they’d have promised to extend them, not just review them.”
Labour’s Council Leader, Cllr Keith Reynolds, added: “The hypocrisy of the Welsh nationalists never ceases to amaze.
“When they are prepared to play a responsible role in setting our council’s budget, instead of abdicating their responsibility and refusing to participate in council budget-setting, they may have some credibility.
“They now make promises for next year, but unsurprisingly have not costed them – or said what other services would have to be sacrificed to meet their aim.”