Lisbon, Oct 14 (IANS): The signing of iconic Spanish goalkeeper Iker Casillas by FC Porto led to a growth in the value of the Portuguese football club's trademark, with shirt sales soaring by more than 10 percent, according to estimates released by the sports daily O Jogo.

According to the data included in the annual accounts of the Dragons, public because of its status as a listed company on the stock exchange, shirt sales generated revenues of four million euros ($4.5 million) last year, with Casillas' shirt making about half a million euros ($568,725)., Efe reported on Tuesday.

"Casillas pays a part of his salary," was the headline in O Jogo on Tuesday, which recalled that no one knows exactly how much of the salary is paid by Porto to the Spanish captain as Real Madrid agreed to pay a relevantly large percentage of it, estimated to be around 2.5 million euros ($2.8 million) net.

The newspaper revealed that the marketing department of Porto expected an increase of three percent in sales of shirts this season, and this forecast has been exceeded by far.

The financial manager of Porto, Fernando Gomes, announced last Friday that thousands of T-shirts with the number '12' of Casillas, planned to be sold in a year, "sold out in a few weeks".