BRUSSELS (AFP) - The mercurial beast known as the financial market spiv or speculator came firmly into euro political leaders' sights on Friday as they arrived for an extraordinary summit in Brussels.

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With the problems facing the shared currency area piling up on the back of the contagious Greek debt crisis, deputy prime minister Maria Teresa de la Vega laid down a clear marker for the EU's current chair Spain by highlighting "speculative attacks."

"Spain will not allow its prestige to be toyed with and that its financial market is put in danger by punishable antisocial behaviour," she said

Like the Portuguese and Greek governments before her, she blamed a sharp drop in Spanish stocks this week on traders deliberately targeting weaker economies, an "unacceptable" source of "hurt," she added.

She said that a reform to Spain's penal code to go before lawmakers would "punish the dissemination of information or rumours with the aim of affecting stock market valuations."

She did not spell out how rumours could be proven to have malicious origins.

European Commission chief Jose Manuel Barroso himself spoke of a "playground" mentality on markets this week, also urging leaders to use new regulation to clamp down ever harder on markets.

Earlier this week, International Monetary Fund and Spanish Prime Minister Jose Luis Rodriguez Zapatero firmly dismissed speculation that Spain was seeking a massive loan from the lending institution.

Rumours began swirling after eurozone finance ministers and the IMF to approved a three-year 110-billion-euro bailout loan package for Greece, fuelling fears that other struggling eurozone nations may need assistance.

Ratings agency Standard & Poor's last week lowered Spain's long-term sovereign credit rating, although Madrid announced on Friday that its economy had finally emerged from recession -- the last major economy to do so.

In Paris, France's market regulator said it too would "punish" speculative attacks, whether at home or among its euro partners.

"Whether it is French banks or foreign banks operating in Paris, whether it is funds in Paris, Berlin or London, is not important," declared Jean-Pierre Jouyet, head of the AMF financial market authority.

"When I hear of speculation, when I see abnormal market movements, there will be inquiries and punishments."

French President Nicolas Sarkozy and German Chancellor Angela Merkel on Thursday urged EU leaders to crack down on the speculative financial trading blamed for worsening certain countries' sovereign debt, and to examine the role of credit rating agencies.

Europe's financial services commissioner, Michel Barnier, has said he wants to "shine a light" on people who prefer to lurk in the shadows.

New rules covering highly speculative hedge and other alternative investment funds are first in Brussels' sights, while curbs on international credit rating agencies are also due in December.

It's all part of a bid to render complicated derivative products and their knock-on effects less 'invisible.'

Banks are being similarly pursued on both sides of the Atlantic, with Goldman Sachs currently under criminal investigation by US federal prosecutors trying to determine whether it committed securities fraud in connection with its mortgage trading.