Traders are selling illegal ivory openly across the European Union through a loophole allowing trade in "antique" items, the campaign group Avaaz charged Tuesday.
Avaaz said nearly all of the 109 ivory pieces it bought in 10 EU countries were found to be illegal after they were tested at Britain's Oxford University.
It said one-fifth of the items came from elephants killed after the global ivory trade was banned in 1989 and three quarters from animals slaughtered after 1947.
EU law requires government certificates for the sale of ivory acquired after 1947 and before 1990, but Avaaz said none of the ivory it bought had a certificate.
"This bombshell evidence proves beyond doubt that illegal ivory is being sold across Europe," Avaaz campaign director Bert Wander said in a statement.
"It must spark the end of this bloody trade. Every day the sale of these trinkets continues is a day closer to wiping out majestic elephants forever," Wander added.
Avaaz bought the items over a four-month period from Belgium, Bulgaria, France, Germany, Ireland, Italy, the Netherlands, Portugal, Spain and Britain.
It said the study counters claims by the European Commission, the 28-nation EU's executive arm, that there was no evidence of illegal ivory being sold.
The new evidence, it added, puts pressure on the EU to ban the trade outright because so many pieces are being passed off as "antique" ivory from elephants killed before 1947, which is legal.
The most recent ivory tested by Oxford's radio-carbon dating unit was from after 2010, Avaaz said.
"The Commission should close the antique ivory loophole, end ivory exports from Europe and shut down the EU's internal trade in raw tusks," Avaaz said.
"This is the only way it can preserve its status as a leader in fighting the wildlife trade and protecting African elephants," it added.
The EU's environment commissioner Karmenu Vella ?pledged to look into the claims after visiting Avaaz's exhibition of illegal ivory outside the Commission in Brussels.
The work is a "very helpful contribution for @EU_Commission as we go through process of planning our next steps," Vella tweeted. "Protecting living elephants the priority."
Avaaz said China, Hong Kong and Britain have all implemented or announced ivory bans over the last year.
It said as many as 30,000 elephants are slaughtered each year, warning the animals could be extinct in the wild within decades if not enough action is taken.
EU law requires government certificates for the sale of ivory acquired after 1947 and before 1990, but Avaaz said none of the ivory it bought had a certificate