The head of Singapore's S-League has defended plans to introduce age restrictions and slash the number of teams after he faced an angry backlash from players.

S-League chief executive Lim Chin, who was jeered and booed at the annual awards ceremony, has also come under fire for comments he made during talks with players of an axed team.

In a leaked recording, Lim is heard telling Tanjong Pagar United players to "know where you stand" after they openly criticised the club's chairman.

Lim told Thursday's Straits Times that rules restricting S-League clubs to five Singaporean players aged over 30, with at least three under 25, were needed to revitalise the competition.

"The demographic of our league is slightly lopsided... and we'd like to correct the balance a little bit... to inject more youth and talent into the league," Lim told the newspaper.

"Once this technical correction has been achieved, we may erase this rule in due course," he added.

Next year's S-League will be reduced from 12 teams to 10 with Tangong Pagar, who reportedly have financial problems, dropping out and Hougang United ordered to merge with Woodlands Wellington.

Debate over the measures comes after naturalised Singaporean striker Aleksandar Duric retired last month at the age of 44, after plundering 330 S-League goals in 16 seasons.

"What is important is that we do good policies that are good for the league... let's bite the bullet," said Lim, a former high-ranking military officer.

Football authorities have for years struggled to raise public interest in the S-League, which competes for attention with wildly popular European competitions like the English Premier League.