VIENNA, Mar. 15 -- The weekly average oil price of the Organization of Petroleum Exporting Countries (OPEC) increased to 110.29 U.S. dollars per barrel last week, the Vienna-based cartel said Monday.

The OPEC basket prices have so far continued to increase for four consecutive weeks.

Analysts believe that this round of continual price hikes is not driven by big changes in supply and demand in oil market, but due to market speculation promoted by the turmoil in North Africa and Arab countries, many of which are OPEC countries.

The unrest in Libya and instability in Saudi Arabia have become the major topic of speculation on the international oil market. The concerns on the security of future supplies of crude oil push oil prices higher.

However, as the chaotic situation of North Africa and the Middle East has not been further aggravated since last weekend, which makes the market speculation cool down. Besides, some profit-taking business operations of the crude oil investors also suppress the oil price to a certain extent.

In addition, the major earthquake in Japan, which would hit its economy tremendously and lead to a huge decline in oil consumption, also affects the relationship of supply and demand in international oil market.

Japan is the world's third largest consumer of crude oil. Its crude oil consumption amounts to 4.37 million barrels per day, accounting for 5.22 percent of total global consumption of crude oil.

Japan is also the fourth largest oil refining country of the world, and its daily processing capacity amounts to 4.62 million barrels. However, its oil consumption is totally dependent on imports.

Press reports showed that the tsunami in Japan last weekend caused by the earthquake has led to the closure of at least five oil refineries, whose combined refinery capacity accounts for one fourth of its total refining capacity.

Japan's crude oil imports are expected to be reduced before the reopening of its ports and its post-disaster reconstruction.

Although the latest OPEC monthly report said that global supply of crude oil remained adequate, the impacts of the situation in Libya and Saudi Arabia on international crude oil market are still cause for concern for the next period of time.

Since Saudi Arabia's current situation is not stable, and as one of the most important crude oil suppliers over the world, there would be huge impact on the international oil prices if there is any unrest in Saudi Arabia.

Overall, in the near future, if there is no further spread of unrest from the Middle East to the major oil producing countries such as Saudi Arabia, the international oil prices would drop with fluctuation.