Japanese customs officials who impounded 200 pens more than a year ago said Friday the writing implements needed a weapons import licence because they were shaped like bullets.

Fountain and ballpoint pens made by US firearms and knife manufacturers, including Smith and Wesson, have been held up by inspectors in Nagoya and Osaka since April 2011.

The pens, which are made from a mixture of titanium and other metals, are fashioned to resemble bullets on the non-writing end.

A Nagoya customs official told AFP that under international regulations, the pens are classified as self-defence weapons, adding: "Special procedures are needed for the import of such products."

But Japanese knife retailer Yamahide Cutlery, which ordered the pens, said the suspension was unfair.

"How could you kill someone with a pen?" asked company president Toshio Yamada. "It is hard to understand."

Yamada said he had no intention of applying for a weapons import licence "because I don't think they are weapons".

The company had successfully imported and sold the pens, which ranged in price between 5,500 yen ($70) and 32,500 yen, from 2008 to 2011.