The leaflet was headed "Third World Clothing Collection" and asked people to donate spare clothes "that will be sent to the Third World, where they will be sorted and worn again".
But complainants claimed the wording was misleading because it used emotive language that implied the leaflet was from a charity. For example, the text said "we urgently need clothing" and "the greatest gift of love is sharing".
The ASA concluded that the flyer, which was distributed in the Leeds area over the last weekend of May, breached Committee of Advertising Practice clauses on substantiation, honesty and truthfulness.
The leaflet included the name and company registration number of clothing collection firm Neringa. But Benediktas Bockus, director of Neringa, denied any involvement with it.
Bockus has since applied to Companies House for Neringa to be de-listed. The application, lodged on 1 September, said the firm had not traded for three months.
An ASA spokeswoman said: "This is the first complaint about Neringa, but we have many complaints about clothing collection companies. Some of them are criminal organisations and it's very difficult to stop them."
Clothes Aid, which makes collections for several charities, told Third Sector that members of the public had complained about a company by the name of Neringa in May and March this year.
Neringa could not be contacted for comment.