(Adds tourism numbers, retail data breakdown, government comment)

* June retail sales rise 5.8% y/y, 5th month of growth

* June tourist arrivals plunge 57.6% y/y vs May's 34.8% drop

* June jewellery, watch sales up 31.8% y/y vs May's 54.8% rise

* Govt says consumption voucher will support retail sector

HONG KONG, Aug 2 (Reuters) - Hong Kong's retail sales climbed for the fifth straight month in June, helped by an improved labour market and a stabilising COVID-19 situation although demand was hampered by weak tourism.

Retail sales in June rose 5.8% from a year earlier to HK$28.1 billion ($3.61 billion), government data showed on Monday. June's increase compared with revised 10.4% growth in May.

"The consumption voucher scheme will help stimulate local consumer sentiment and provide support to the retail sector," a government spokesman said, referring to electronic vouchers given to certain consumer to spend in retail stores.

He urged the community to keep the epidemic under control and strive towards more widespread vaccination, in order for a broader economic recovery.

In volume terms, retail sales in June grew 2.8% from a year earlier, compared with a revised 7.7% surge the previous month.

For the first half of 2021, total retail sales increased 8.4% in value terms and rose 7.1% in volume.

Online retail sales in June jumped 63.8% in value year-on-year, compared with a revised growth of 52.9% in May.

Sales of jewellery, watches, clocks and valuable gifts, which before the pandemic relied heavily on Chinese tourists from the mainland, climbed 31.8% in June versus a 54.8% surge in May, the data showed.

Clothing, footwear and allied products rose 15.3% in June.

Tourist arrivals in June slumped 57.6% from a year earlier to 6,200 after posting a 34.8% drop in May. The city recorded its first growth in arrivals in April, of 38.3%, after 21 straight months of decline but overall numbers were tiny.

Hong Kong's economy lost some momentum in the second quarter but still expanded by 7.5% from a year earlier, as domestic and global activity continued to recover. The government maintained its full-year growth forecast at 3.5%-5.5%.

Seasonally adjusted unemployment slipped to 5.5% in April-June, from 6% in March-May and 6.4% in February-April with the labour market expected to improve further as coronavirus cases remain close to zero.

The government has urged more people to get vaccinated to pave the way for a broader based economic recovery. About a third of the population has received the recommended two doses and less than half have had at least one dose. ($1 = 7.7751 Hong Kong dollars) (Editing by Jacqueline Wong)