Britain insisted on Tuesday that it was keeping an open mind on how to respond to Russian aggression against Ukraine, after the emergence of an apparently official document suggesting London opposed trade sanctions.
Foreign Secretary William Hague said that "all options remain on the table on the diplomatic and economic side" but said Britain would not make any announcements until European Union leaders meet to discuss the crisis on Thursday.
He acknowledged the "regrettable" security breach that resulted in a press photographer snapping an official document being carried into a meeting at Prime Minister David Cameron's Downing Street office on Monday.
It appeared to be a briefing note and recommended that "the UK should not support for now trade sanctions... or close London's financial centre to Russians".
London is an increasingly popular destination for wealthy Russians and the banks and trading houses of the City financial district attract substantial amounts of Russian capital.
Updating the House of Commons after his visit to Kiev on Monday, Hague rejected claims the photo blunder risked Britain's leverage during intense diplomatic negotiations.
"Anything that is written in one document being carried by one official is not necessarily any guide to the decisions that will be made by Her Majesty's government," Hague said.
"Our options remain very much open on this subject."
Putting aside the issue of sanctions, Hague noted that the reaction of the markets showed "there are major risks for Russia economically" in its actions across the border.
Russian stock markets crashed almost 10 percent and the ruble plunged to historic lows in value against the dollar and euro on Monday over concerns about the crisis.
"In the medium to long term, Russia needs the economic cooperation of European nations just as much or more as they need the cooperation of Russia," Hague said.
The minister has repeatedly warned of the "consequences and costs" of Russia's intervention in the ex-Soviet state but he and Cameron have yet to spell out what these might be.
EU foreign ministers warned Moscow on Monday to de-escalate or risk sanctions, including the suspension of long-running talks on easing EU visa requirements for Russian citizens.
Further "targeted measures" may also be considered, including visa bans or asset freezes against senior figures as well as suspending mutual accords, EU sources said.
Hague was cautious on individual asset freezes, saying: "Given our experience on sanctions being applied to several parts of the world in recent years, we have to be legally very sure of our case to apply sanctions on individuals."
He added: "The options are open but any measures we take must be well-judged and well-targeted and united in the European Union and the Western world more generally."
The rhetoric from the United States has been tougher, with Washington suspending military cooperation and promising movement on a broad range of sanctions later this week.