ATHENS (Reuters) - Greece has ordered some businesses not to let their employees perform heavy outdoor duties during afternoon hours this week as the country sizzles in yet another heat wave.

Builders, food delivery riders, couriers and shipwrights are among those having to pause work from midday till 5 pm from Tuesday till Friday as the mercury is expected to reach 42-43 Celsius in parts of Greece, the labour ministry said.

Several regions of the world, from the United States to India, have similarly been suffering this summer from extreme heat that has triggered power outages and wildfires.

Greece has repeatedly seen high temperatures disrupt daily activities since June and hundreds of wildfires have broken out, fanned by strong winds, following the warmest winter on record that scientists link to global climate change.

Meteorologists say temperatures will not drop by much before the end of the month.

With most of Greece seeing little or no rain in months, many of its islands, which draw millions of tourists over the summer, are also grappling with water shortages.

"At times I get headaches, dizziness, blurry vision," 44-year-old municipal street cleaner Adamantia Krassa said.

"In such high temperatures, I believe we should stop working after a certain hour, pause and then resume."

A Red Cross mobile unit was stationed on Syntagma Square in central Athens to offer assistance to passers-by.

"We are going through a prolonged period of high temperatures. All this physical strain has negative effects on the human body," said the unit's coordinator, Dimitra Tsekoura.

At least six tourists, including well-known British television presenter Michael Mosley, died last month as a result of the intense heat.

(Reporting by Valentini Anagnostopoulou and Angeliki Koutantou; Editing by Gareth Jones)