* Regional police call for neutrality
* Government moves to force control
* Tension in Barcelona, unity in Madrid
* Peaceful resistance planned (recasts, adds background)
MADRID/BARCELONA, Oct 28 (Reuters) - Catalonia's police force told its officers to remain neutral in the struggle over the region's fight for independence from Spain, a step towards averting possible conflict as the Madrid government starts to impose control on Saturday.
Spanish Prime Minister Mariano Rajoy dismissed the Catalan government, took over the administration and called a new election after the regional parliament made a unilateral declaration of independence on Friday, aggravating Spain's worst political crisis in four decades.
The independence declaration, though dramatic, was almost immediately rendered futile by Rajoy's actions. Other European countries and the United States also rejected it and expressed support for Spain's prime minister.
But emotions are running high in Catalonia and the next few days will be tricky for Madrid as it embarks on enforcing direct rule on the ground. Rajoy designated Deputy Prime Minister Soraya Saenz Santamaria to oversee the process.
The regional parliament's vote to declare Catalonia a separate nation, which was boycotted by three national opposition parties, capped a battle of wills between the independence movement, headed by the now-sacked Carles Puigdemont and the Madrid government.
The separatists say a referendum held on Oct. 1 gave them a mandate for independence. However, less than half of eligible voters turned out for the ballot, which Madrid declared illegal and tried to stop.
Opinion polls regularly show that more than half of the 5.3 million people who are eligible to vote in the wealthy northeastern region do not want to break from Spain.
In an effort to defuse tensions, the regional police force urged its officers to behave in a neutral manner and not to take sides, an internal note seen by Reuters showed.
There have been doubts over how the Mossos d'Esquadra, as the Catalan police are called, would respond if ordered to evict Puigdemont and his government.
The force is riven by distrust between those for and against independence and is estranged from Spain's national police forces, Mossos and national police officers have told Reuters. Some Catalan police officers stood between national police and those trying to vote during the banned referendum.
"Given that there is it is likely to be an increase in gatherings and rallies of citizens in all the territory and that there are people of different thoughts, we must remember that it is our responsibility to guarantee the security of all and help these to take place without incident," said the memo, which had no name attached to it.
The Madrid government also sacked the force's chief of Catalonia's regional police force, Josep Lluis Trapero, the official gazette announced on Saturday.
Trapero became a hero to the secessionists after his force took a much softer stance than national police in enforcing the government ban on the independence referendum.
Spain's High Court on Oct. 16 banned Trapero from leaving the country and seized his passport as part of an investigation for alleged sedition, although it did not order his arrest.
Prosecutors say he failed to give orders to rescue national police trapped inside a Barcelona building during pro-independence protests last month.
In Barcelona, thousands of independence supporters packed the Sant Jaume Square in front of the regional headquarters on Friday night, waving Catalan flags and singing traditional songs in the Catalan language as bands played. There was no trouble.
But some analysts say that street confrontation is possible as the Madrid government enforces control.
The main secessionist group, the Catalan National Assembly, on Friday called on civil servants not to follow orders from the Spanish government, but it stressed they should mount "peaceful resistance".
A pro-independence trade union, the CSC, called a strike from Monday through to Nov. 9. The government said it would ensure a minimum service.
MADRID SAYS VIVA ESPANA
A pro-unity rally was due to take place in Madrid on Saturday afternoon, an indication of the resentment the independence drive has caused in the rest of Spain.
The chaos has also prompted a flight of business from Catalonia, which contributes about a fifth of Spain's economy, the fourth-largest in the euro zone. Markets have dipped and risen on the roller-coaster of developments.
European leaders have denounced the push, fearing it could fan separatist sentiment around the continent.
Catalonia is one of Spain's most prosperous regions and already has a high degree of autonomy. But it has a litany of historic grievances, exacerbated during the 1939-1975 Franco dictatorship, when its culture and politics were suppressed.
The new regional election will be held on Dec. 21. But it is not certain whether this can resolve the crisis as it could increase the numbers of independence supporters in parliament and take things full circle.
(Reporting by Sonya Dowsett and Jesús Aguado, writing by Angus MacSwan, additional by Andrés González and Tomás Cobos, editing by Alexander Smith)