Low crude oil prices and weak refining margins have hit ExxonMobil and rival Chevron’s profits in Q1 of 2016.

ExxonMobil reported a profit of $1.8 billion, a sharp decline from $4.94 billion for the same period in 2015 and its lowest quarterly profit since 1999.

Revenue dropped 28% to $48.7 billion, but it had strong results from its petrochemicals division.

Chevron has reported a quarterly net loss of $725 million.

That compared with a net profit of $2.57 billion for the same period in 2015 and was worse than analysts had expected.

Chevron CEO John Watson said: “We are controlling our spend and getting key projects under construction online, which will boost revenue.”

ExxonMobil shares rose 1.4% in New York on April 29, while Chevron fell 0.6%.

Meanwhile, oil prices hit their highest levels of the year on April 29, driven up by lower US production and a weak dollar.

Brent crude was up 12 cents at $48.26 a barrel in afternoon trading, while US oil rose 57 cents to $46.60.

US oil production has continued to fall in recent months, easing concerns about oversupply, while the dollar has lost almost 2% of its value against other global currencies in the past week.

A weaker US dollar typically contributes to a rise in oil prices, because oil is priced in dollars. When the dollar weakens against other currencies, oil becomes cheaper to buy, pushing up demand.

However, the latest rise in oil prices may be limited by a future increase in Middle East production, according to a note released by Deutsche Bank.

Iraq and the UAE are likely to raise production after maintenance issues are resolved, Deutsche indicated, and Saudi Arabia may also increase production significantly.

However, this may be tempered by events in Latin America, where Venezuela is struggling to maintain its crude output, according to a report from Eurasia Group.

Eurasia Group reported that low oil prices over the past two years have meant Venezuela’s government is running out of cash to keep its state-owned oil pumps operational.