HAVANA, Cuba - Cuba's Communist leaders vowed not to cede any ground to "the enemy," even as they pledged to fight corruption and continue overhauling the island's listing Marxist economy with an injection of free market reform.

No word of long-awaited political changes -- including an April pledge by President Raul Castro to implement term limits -- seeped out of the first day of the closed-door party conference. Nor was there any hint of changes to the aged upper ranks of the party hierarchy. President Raul Castro is 80, and his two top deputies are 81 and 79, respectively.

Castro has spoken of the need to revitalize the island's leadership, but has complained there are few young leaders ready to step up. He, or his now-retired brother Fidel, have ruled the country since their 1959 revolution.

"Making the necessary changes, but without the smallest concession to the enemy," read the headline in Sunday's official Juventud Rebelde newspaper, an apparent reference to the United States and other government opponents.

The theme was echoed by delegates at the conference in snippets of the session shown on state television

"The enemy is waiting to create internal problems for us," Angel Bueno warned fellow attendees.

Raul Castro was to address the delegates in a closing speech Sunday, according to state-run website Cubadebate, though it was not clear if his words would be televised or rebroadcast at some point. Attendees did pledge to boost the ranks of women, Afro-Cubans and young people in the party and government, and noted that women currently make up 37 per cent of the government, and 41 per cent of delegates to the island's National Assembly.

But there were no concrete resolutions, and Castro's recent comments not to expect fireworks out of the internal meetings dampened expectations any major announcements were coming.

The meetings are a follow-up to last April's historic party summit, which opened up long-shut doors of economic opportunity by green-lighting the legalization of home and car sales, expansion of private-sector activity and extension of loans to support farmers, entrepreneurs and homeowners.

Foreign journalists were not allowed access to the weekend event.

State-run website Cubadebate showed photos of Castro presiding over the conference wearing a grey blazer and a dark, open-collar shirt, with what appeared to be a small bandage on the tip of his nose. There was no word of any appearance by Fidel Castro, who was greeted with a standing ovation and some tears at the April congress.

In a brief snippet of video posted on Cubadebate, Vice-President Jose Ramon Machado Ventura said in a keynote speech that the conference would focus on "the everyday work of the organization."