TOKYO (Reuters) - Japan's core consumer inflation probably picked up in June for a second straight month, a Reuters poll of 18 economists showed, keeping the central bank under pressure to raise interest rates.

Separate data from the Ministry of Finance will likely show that export growth slowed down year-on-year in June, undershooting import gains and leaving behind a trade deficit.

Data from the internal affairs and communications ministry is expected to show on July 19 that the core Consumer Prices Index, which excludes fresh food, rose 2.7% year-on-year in June, faster than the previous month's 2.5% rise.

That would mean that inflation has remained above the Bank of Japan's 2% target for the 27th straight month, concerning the BOJ which reckons inflation is being powered by external cost pressures, rather than the domestic demand which policymakers are trying to encourage.

In Japan, inflation has been fuelled by higher raw materials and fuel import costs, exacerbated by a weak yen.

Normalising monetary policy will need a "virtuous growth cycle" materialising in Japan, the BOJ has said, in which solid wage hikes are accompanied by durable inflation and household consumption.

The data will be scrutinised by the BOJ at its policy-setting meeting on July 30-31 at which the central bank will review its projections for GDP growth and inflation.

Some investors are betting the central bank will raise interest rates in July, while cutting its government bond buying as a step towards normalising monetary policy. Earlier this year the BOJ began unwinding its unconventional policy, raising interest rates in March for the first time since 2007.

Japan's exports likely rose 6.4% on year in June, slowing sharply from the previous month's 13.5% gain. Imports were forecast to have grown 9.3% versus 9.5% in May, resulting in a trade deficit in June of 240 billion yen ($1.51 billion). The MOF trade data is due to be released on July 18.

($1 = 159.1800 yen)

(Reporting by Tetsushi Kajimoto; Editing by Toby Chopra)

By Tetsushi Kajimoto