The marks made by self-inking pens on ballot papers for the election will not become invisible, said the Elections Department (ELD), debunking false claims.

ELD said yesterday that it was aware of false information being circulated in messages and online posts, which claimed that ballot papers and self-inking pens provided for the election have been treated such that marks made on the ballot papers will become invisible after several minutes.

"ELD would like to state categorically that this is not true," the department said in a statement.

The marks made using the self-inking pens are permanent, it said.

In fact, the ink is oil-based and water-and temperature-resistant, said ELD, adding that similar pens have also been used in elections in other countries like South Korea.

ELD also said the ballot papers used for this election are no different from those in past elections, and are printed under tight security conditions. "It will not be possible for the ballot papers to be put through any additional treatment under such a tightly controlled environment," it said.

Self-inking pens were introduced following feedback in previous elections that some voters, especially seniors, had difficulty gripping regular pens to mark their votes. The pens allow voters to easily mark an "X" on the ballot paper by applying pressure, like a chop.

Voters are also allowed to take their own pens to mark the ballot papers.

"ELD is committed to ensuring voting security and secrecy, and has put in place rigorous controls at every step of the voting process to ensure this," the department said.