(Refiles to correct 3rd paragraph to say 'long bets', not 'net long bets')
June 24 (Reuters) - Currency speculators increased their net short positions against the British pound in the week before the United Kingdom voted to exit the European Union, according to data from the Commodity Futures Trading Commission released on Friday.
The number of contracts for net short positions against the pound rose by more than 15,000 for the week ending June 21. That was still well below a five-year high touched during the week ending June 7 when net short positions rose to more than 66,000.
While net shorts rose overall, it was due to a reduction in long bets rather than an increase in shorts. The number of short bets actually decreased by almost 5,000 contracts, data showed, but long bets fell by nearly 20,000.
There were a total of 51,947 net shorts against sterling in the last week for a total value of negative-$4.75 billion. The positions were tracked through Tuesday, two days before Britain held its landmark vote in which citizens decided to leave the European Union on Thursday. be short a currency is to bet it will decline in value, while being long is to wager that its value will rise.
Sterling fell to its lowest level against the U.S. dollar in 31 years on Friday, following the 'Brexit' vote. It plunged as much as 10 percent from its late Thursday levels to $1.3228, hitting its weakest level since before the 1985 Plaza Accord.
Speculators raised their net long bets on the U.S. dollar to $6.62 billion. Investors had cut bets by nearly $8 billion the week before to around $2.7 billion, the smallest net long positions since April 12.
Net long positions on Japan's yen, a traditional safe-haven currency, decreased during the week.
The Reuters calculation for the aggregate U.S. dollar position is derived from net positions of International Monetary speculators in the yen, euro, British pound, Swiss franc and Canadian and Australian dollars.
Japanese Yen (Contracts of 12,500,000 yen) $-6.242 billion
June 21, 2016
Prior week
week
Long
79,398
77,703 Short
27,102
22,013 Net
52,296
55,690 EURO (Contracts of 125,000 euros) $8.619 billion
June 21, 2016
Prior week
week
Long
88,639
104,510 Short
149,985
160,999 Net
-61,346
-56,489 POUND STERLING (Contracts of 62,500 pounds sterling) $4.755 billion
June 21, 2016
Prior week
week
Long
41,707
61,706 Short
93,654
98,367 Net
-51,947
-36,661 SWISS FRANC (Contracts of 125,000 Swiss francs) $-0.829 billion
June 21, 2016
Prior week
week
Long
24,016
28,492 Short
17,635
21,362 Net
6,381
7,130 CANADIAN DOLLAR (Contracts of 100,000 Canadian dollars) $-0.202 billion
June 21, 2016
Prior week
week
Long
40,664
42,394 Short
38,069
23,954 Net
2,595
18,440 AUSTRALIAN DOLLAR (Contracts of 100,000 Aussie dollars) $0.524 billion
June 21, 2016
Prior week
week
Long
38,611
39,512 Short
45,654
46,290 Net
-7,043
-6,778 MEXICAN PESO (Contracts of 500,000 pesos) $1.85 billion
June 21, 2016
Prior week
week
Long
13,509
16,894 Short
82,389
82,513 Net
-68,880
-65,619 NEW ZEALAND DOLLAR (Contracts of 100,000 New Zealand dollars) $0.217 billion
June 21, 2016
Prior week
week
Long
30,013
29,558 Short
33,058
33,376 Net
-3,045
-3,818