UPDATE 1-EU executive may suspend Slovak mail law

(Adds more detail, background)

BRUSSELS, June 18 (Reuters) - Slovakia could be ordered to suspend a law that gives a postal operator a monopoly over some mail, the European Commission said on Wednesday.

Before February, the Slovak postal system was open to competition and several private companies were active in the sector. But then the government amended the law, reserving the delivery of some mail to the incumbent postal operator.

The European Union executive started proceedings against Slovakia to verify whether the change to the law broke EU rules.

"An activity which had been successfully liberalised should not be re-monopolised to the benefit of the incumbent operator," EU Competition Commissioner Neelie Kroes said in a statement.

EU member states have agreed to open up their 88 billion euro postal markets to full competition from the start of 2011, with an extra two years for new member states.

The EU executive wants Slovakia to clarify the recent amendments to its postal law as they may infringe the bloc's rules aimed at stopping a single company abusing its dominant position in the market.

In a rare move, the executive has given Slovakia two weeks to comment on a possible interim measure whereby Brussels would order the law to be suspended pending a probe into its legality.

"We think it's justified because of the risk of serious irreparable harm to competition in the postal sector in Slovakia," Commission spokesman Jonathan Todd told a regular news briefing.

The Commission said the amendments in question extend the monopoly on the delivery of so-called hybrid mail.

Big companies email the content of a letter, such as an invoice, to the postal operator, which then prints it out and delivers it to customers in the traditional way.

This activity was open to competition before the amendments.

"The Commission alleges as a consequence, postal operators which had entered this market are now prevented by law from continuing their activity, and their commercial viability is at risk," the executive said. (Reporting by Huw Jones, editing by William Schomberg, Paul Bolding)