* Ex-antitrust, tech commissioner in spotlight after Bahamas leaks
* Commission's president Juncker seeks clarification from Kroes
* Bahamas documents trigger new calls to fight tax avoidance (adds new comments from Commission, political reactions)
By Francesco Guarascio and Alastair Macdonald
BRUSSELS, Sept 22 (Reuters) - The European Commission said on Thursday it was looking into whether to take action against former EU commissioner Neelie Kroes for failing to declare a directorship of an offshore firm in the Bahamas.
Kroes, who was the Commission's anti-trust chief and then oversaw digital affairs under former president Jose Manuel Barroso for a decade until 2014, confirmed to newspapers which published leaked Bahamas documents that she should have declared her interest in the offshore company.
A spokesman for the European Commission said the EU executive is seeking further clarification from Kroes in addition to information now provided by the former commissioner. He did not rule out sanctions for Kroes if it was established that she failed to declare the directorship in the Bahamas.
The revelation comes at an awkward time for the Commission, which is battling to regain public trust following the British vote to leave the Union. Against a rise of nationalist and anti-establishment parties across Europe, it is fighting to change an impression that it is too close to big business.
Commission President Jean-Claude Juncker has already made clear his irritation with his predecessor Barroso for taking a job with U.S. bank Goldman Sachs this summer.
Though the Commission does not think Barroso breached its code of conduct, an ethics panel will report soon on whether his move to a bank which some Europeans blame for the EU financial crisis was in line with an obligation to act with integrity.
"There are certain things that even the strictest rules like ours cannot fix," the Commission spokesman said.
"This was the case of our former president who made a choice to go to work for a certain bank, and this is now the case of the former commissioner who apparently did not respect the rules and did not tell the Commission about it," he added.
"Commissioners' conduct past and present must be exemplary," European Parliament President Martin Schulz tweeted, saying the Bahamas incident placed a "shadow on Kroes".
Kroes, a Dutch liberal politician, also came in for criticism from the Commission earlier this month after she publicly questioned the decision of the current competition commissioner, Margrethe Vestager, to demand 13 billion euros in back taxes from Apple Inc in Ireland.
A Commission spokesman noted in reaction that the Dutch former digital commissioner now holds a position at U.S. ride-sharing company Uber, which she had openly supported during her mandate as tech commissioner in its legal battles with taxi drivers' organisations in Europe.
"As with other similar revelations, we should be very cautious and deal with this in an orderly manner, avoiding any premature conclusions," said a spokesman for the centre-right group, the largest in the European Parliament.
"The leaks have yet again underlined that what we are facing is a structural problem and not a scandal about individuals," he added, calling for a quick adoption of an EU blacklist of tax havens.
The European Commission wants to establish a common blacklist by the end of next year, and impose sanctions on listed countries.
It published in September a preliminary list of 81 countries and jurisdictions that have a higher chance of facilitating tax avoidance, on which "the Bahamas were flagged as a high-risk country in terms of problems with its taxation system", the commissioner responsible for taxation, Pierre Moscovici, said.
Anti-corruption advocacy group Transparency International called on countries worldwide to publish the details of who owns and controls companies established in their jurisdictions. The EU Commission proposed in July new transparency rules on company ownership, which will need approval from the 28 EU member states. (Editing by Catherine Evans)