Collins was the IRA's leader in 1922

The letter, written months before he was killed in 1922, details his opposition to the partition of Ireland.

The letter was bought by a private collector at Friday night's auction after bidding that went on for just two minutes.

Beforehand, it had been predicted the letter would fetch �5,000 but ended up being sold for six times more than any of his previous letters that were auctioned.

Collins sent the three-page document to a leading Derry republican, Louis J Walsh.

In it, Collins outlined his opposition to the partition of Ireland and the formation of Northern Ireland as a separate state within the United Kingdom.

'Unreasonable stance'

It was written after he returned to Dublin from a meeting in London with Churchill and unionist leader James Craig.

He said Craig's stance on partition was seen as "an unreasonable one and not ours".

"All the British statesmen are agreed that it was most disastrous on Craig's part to talk about agreeing to nothing less than the six county area," he wrote.

"It would be far better to fix our minds for a time on a united Ireland, for this course will not leave minorities which would be impossible to govern."

Auctioneer Peter Sheen said the item was very important.

"So far as Michael Collins' correspondence is concerned virtually nothing survived.

"All that survived are his love letters and a few brief snippets, but there is very little in terms of political correspondence."

The letter spent decades in the Walsh family but was sold by a private collector who purchased it a number of years ago.