NEW DELHI: India on Tuesday summoned the Iranian Ambassador to lodge a strong protest over the detention of its oil tanker over last 16 days and sought an "unconditional" release of the vessel.

Foreign secretary Sujatha Singh summoned Iranian ambassador Gholamreza Ansari to lodge the protest and demanded early release of the tanker detained by Iranian Revolutionary Guards Corps (IRGC) since August 12.

The tanker was seized in Persian Gulf while carrying crude from Basrah in Iraq and was taken to Bandar Abbas port.

"Foreign secretary has conveyed government's strong concern at the continued detention of our ship in Port Bandar Abbas and Government of India's expectation that the ship would be released at an early date and that crew members would be treated with all due consideration and courtesy in keeping with international norms. Officials of both sides will make another effort to resolve this issue amicably," spokesperson in the ministry of external affairs said.

He also noted that it was for the second time since MV Desh Shanti was detained by Iranian authorities, India had called the Iranian Ambassador. The last such meeting took place on August 16, he said.

India was constantly engaging with Iran --both in Tehran and here, external affairs minister Salman Khurshid said while asserting that it was important that New Delhi does not concede any point and the ship has to be released "unconditionally".

Hoping that Iran will address the issue as two weeks "is really too long for something like this to happen", Khurshid said, "I am sure the decision has not been taken at the level of Central government of Iran."

Khurshid also said he was convinced that there was no scope for establishing any pollution caused by the ship. "We are little bit perplexed why this had happened and who has taken the decision."

Meanwhile, the Indian ambassador in Tehran travelled to Bandar Abbas and met the captain of the ship and the other embassy staff met the crew, official sources said.

