* Organisers say protest represents "silent majority"

* Catalan leader could declare independence on Tuesday

* Spain PM Rajoy doesn't rule out suspending Catalan autonomy

* Rajoy says could remove Catalan regional government

By Sam Edwards

BARCELONA, Oct 8 (Reuters) - Tens of thousands of people took to the streets of Catalonia's capital Barcelona on Sunday to express their opposition to any declaration of independence from Spain, showing how divided the region is on the issue.

The protesters rallied in central Barcelona, waving Spanish and Catalan flags and banners saying "Catalonia is Spain" and "Together we are stronger", as politicians on both sides hardened their positions in the country's worst political crisis for decades.

Spanish Prime Minister Mariano Rajoy said on Saturday he would not rule out removing Catalonia's government and calling a fresh local election if it claimed independence, as well as suspending the region's existing autonomous status.

The stark warning came days before Catalan leader Carles Puigdemont is expected to address the region's parliament, on Tuesday, when he could unilaterally declare independence.

"We feel both Catalan and Spanish," Araceli Ponze, 72, said as she rallied in Barcelona. "We are facing a tremendous unknown. We will see what happens this week but we have to speak out very loudly so they know what we want."

The wealthy northeastern region of 7.5 million people, which has its own language and culture, held an independence referendum on Oct. 1 in defiance of a Spanish court ban.

More than 90 percent of the 2.3 million people who voted backed secession, according to Catalan officials. But that turnout represented only 43 percent of the region's 5.3 million eligible voters as many opponents of independence stayed away.

The Spanish government sent thousands of national police into the region to prevent the vote. About 900 people were injured when officers fired rubber bullets and charged crowds with truncheons in scenes that shocked Spain and the world, and dramatically escalated the dispute.

Losing Catalonia is almost unthinkable for the Spanish government.

It would deprive Spain of about 16 percent of its people, a fifth of its economic output and more than a quarter of its exports. Catalonia is also the top destination for foreign tourists, attracting about a quarter of Spain's total.

The political stand-off has pushed banks and companies to move their headquarters outside Catalonia. Concern is growing in EU capitals about the impact of the crisis on the Spanish economy, the fourth largest in the euro zone, and on possible spillovers to other economies.