* Azarov says enough grain for home needs and export demands
* Government had earlier proposed limits on wheat, barley
* Customs says it blocking 12-15 ships carrying grain
(Adds customs on numbers of ships blocked paragraphs 11-12)
SIMFEROPOL, Ukraine, Sept 10 (Reuters) - Ukraine's government will not introduce any limits on grain exports because it has enough grain to cover domestic needs and export demands, Prime Minister Mykola Azarov said on Friday.
"We do not plan any kind of limits on exports," Azarov told regional officials in the southern Crimea region.
"Despite the drought, we have harvested enough grain to cover all export and domestic needs," he said.
World wheat prices surged to two-year highs in early August as drought devastated the harvest in Russia, which announced a sudden grain export ban.
After the searing drought in July and August, Ukraine's grain crop is likely to fall to 40 million tonnes from 46 million in 2009, according to the ministry of agriculture. But it is still well above domestic needs of 26 million tonnes.
After Russia introduced a grain export ban in August, the Ukrainian government proposed limiting exports of wheat and barley to 2.5 million tonnes between September and December, though it then said that a final decision would be made only in October.
Deputy Prime Minister Viktor Slauta this week said Ukraine was able to export up to 16 million tonnes of grain this season, against 21.5 million in 2009/10.
In spite of what the government says, the customs service is carrying out de facto curbs on exports by holding up shipments in Black Sea and Azov Sea ports, trade sources say.
The customs service says its checks are directed at stopping an outflow of illegal grain. Its activities cut the grain export volume to about 2 million tonnes in the first two months of this season, compared with 4 million in the same 2009/10 period. The grain traders' union UZA said this week that customs officials had blocked 24 vessels with 379,647 tonnes of grain, mostly wheat, for export without offering any explanation.
A senior customs official said on Friday that the customs service was at present holding between 12 and 15 ships loaded with grain but did not say how much grain was on board.
Since the beginning of August, the customs service has cleared about 500,000 tonnes of grain for export, Sergiy Syomka, deputy head of the service, told journalists.
UkrAgroConsult agriculture consultancy said on Friday that at least 450,000 tonnes of grain were blocked by customs in ports.
"Milling wheat remains the most difficult export commodity in Ukraine due to Customs' acts. UkrAgroConsult believes present time at least 450,000 tonnes of grains are being blocked at the ports," the consultancy said in a report.
"Despite the attractive prices and strong demand, most exporters are not willing to work with milling wheat. The main market players are millers," UkrAgroConsult said. (Reporting by Pavel Polityuk; editing by Richard Balmforth and Jane Baird)