The pound dropped Tuesday against its main rivals after a series of deadly attacks shook Brussels and were seen potentially boosting support for a British exit from the European Union.

The pound GBPUSD, +0.02% was down 1.2% at $1.4204 late Tuesday in New York, its largest one-day loss since Feb. 24—just days after U.K. Prime Minister David Cameron said a referendum on the country’s continued membership in the European Union would take place on June 23, sending the currency spiraling to seven-year lows.

The British currency had traded at $1.4375 late Monday in New York.

Meanwhile, the euro EURGBP, -0.02% rose 1% against the pound to 78.94 pence, from 78.20 pence late Monday in New York.

Read: Stock futures trim losses but remain lower after deadly attacks in Belgium

Also read: Brussels Metro rocked by explosion after deadly airport attack

See also: American Airlines says all employees in Brussels are safe

“ “There’s been limited damage to the euro. More damage is being seen in sterling because this is being seen as adding fuel to the Brexit fire.” ” — Douglas Borthwick, head of currency trading at Chapdelaine & Co.

Despite Cameron’s earlier warning that the attack shouldn’t be used for political purposes, analysts said the bombing in Brussels would likely increase support for a break with the EU.

“There’s been limited damage to the euro. More damage is being seen in sterling because this is being seen as adding fuel to the Brexit fire,” Douglas Borthwick, head of currency trading at Chapdelaine & Co.

Analysts said that pro-Brexit politicians would likely use the attacks to support calls to strengthen border restrictions.

“While the Brexit camp has been stressing the loss of sovereignty by being a member of the EU, immigration and border controls have been central to their arguments,” said Marc Chandler, global head of currency strategy at Brown Brothers Harriman.

Haven rally fades

After rallying early in the global day as investor confidence was shaken in the wake of the Brussels attacks, the Swiss franc and the Japanese yen USDJPY, -0.01% had largely pared their declines by early afternoon New York Time.

The dollar was up slightly at ¥112.33 late Tuesday after sinking by as much as 0.5% earlier in the session. The buck traded at ¥112.08 late Monday in New York.

The Swiss franc EURCHF, +0.00% bought 0.9164 euro in recent trade, after trading 0.3% higher at 0.9196 earlier in the session.