Saudi Arabia, Opec’s biggest oil exporter, could raise crude output by more than a million barrels a day straight away if there is demand for it, according to Deputy Crown Prince Mohammed bin Salman al-Saud.

The kingdom stuck to its policy of freezing oil production only if all major producers including Iran do the same, the prince said in an interview with the US-based news agency Bloomberg.

His comments come as at least 15 nations prepare to gather in Doha on 17 April to discuss freezing output at January levels in order to stabilise an oversupplied market. Iran’s deputy oil minister said the country “saw no reason” to attend the talks because it needs to get back to the level it produced before international sanctions against Tehran.

Saudi Arabia could increase crude output to 11.5 million barrels a day immediately and further hike production to 12.5 million in six-to-nine months, said the prince, who also heads Saudi Aramco, the world’s biggest oil producer, which pumped 10.2 million barrels a day in March.

If the kingdom chose to increase investment in its oil industry, total production capacity could be increased to 20 million barrels a day, the prince added.

“I don’t suggest that we should produce more, but we can produce more,” he said. “We can produce 20 million barrels of oil per day if we invested in production capacity, but we can’t produce beyond 20 million.”

Saudi Arabia set a crude production record of 10.564 million barrels a day in June 2015. The country ramped up output after it led Opec to change its strategy in November 2014, to protect the group’s market share instead of supporting prices by cutting production.

Saudi production has been steady at about 10.2 million since January – the proposed level of the freeze. Russia pumped 10.9 million barrels a day, also little changed from January.

Saudi Aramco has said it will press ahead with new developments and will not cut investments because of the plunge in crude prices. The company is planning to complete an expansion of the Khurais oil field’s output to 1.5 million barrels a day in 2018.

Saudi Arabia is producing below its potential capacity because it only responds to demand, the prince said. “If we produced more oil than there is demand, we would destroy many markets. So we consider supply and demand, and we look at any demand we receive and we deal with it.”