NEW DELHI/WASHINGTON  - Afghan President Hamid Karzai arrived in India Thursday for a four-day visit, with Washington hoping New Delhi can persuade him to sign a deal allowing US troops to stay on post-2014.

Karzai is scheduled to meet Indian Prime Minister Manmohan Singh and Foreign Minister Salman Khurshid in the capital during the trip, which will also see him hold talks with business leaders and students in western Pune city.

The Afghan president, a frequent visitor to India, landed in New Delhi for the start of the four-day trip, the Indian Ministry of External Affairs said, tweeting a photo of Karzai.

The president’s office said he would “discuss ways to enhance bilateral relations and cooperation” with India in the build-up to the departure of some 75,000 NATO troops from Afghanistan at the end of next year.

Karzai has long enjoyed close relations with New Delhi which is keen to ensure the exit of the US-led NATO troops does not trigger a return to power in Kabul of the Taliban, which was allied with India’s historic rival Pakistan.

India has poured $2 billion in reconstruction aid into Afghanistan, and Karzai is expected to plead for further support, including military assistance, in his meetings.

A senior US official said this week that he hoped India could help persuade Karzai to ink an agreement for some US troops to stay in Afghanistan after 2014, despite Karzai’s insistence that he will leave the decision to his successor.

Meanwhile, the White House would like Afghan President Hamid Karzai to sign a bilateral security agreement by the end of the year, but the deadline could slip into early January, a spokesman said on Wednesday.

The United States has insisted that Karzai sign the pact by the end of the year. The deal would permit the United States to keep troops in Afghanistan beyond the end of 2014 to support Afghan forces and conduct limited counterterrorism activities.

“If you’re asking, ‘Does that mean that if they sign it on January 10th, that’s going to be a huge problem?’ Probably not,” said Josh Earnest, a deputy spokesxman for the White House.

“What will be a significant problem is if there is not quick action taken to get this signed,” Earnest told a news briefing.

The United States says it gave Afghanistan a year-end deadline to sign the agreement because it needs time to plan its troop presence after 2014. Without a deal, Washington says it would have to withdraw its entire force of some 44,500 troops by the end of 2014. Other NATO nations could follow suit.

Afghan elders and politicians endorsed the pact last month, but Karzai surprised Washington by introducing new conditions for his signature.

Meanwhile, an accidental explosion in an arms depot shook central Kabul on Thursday, with Afghan officials moving quickly to allay fears of an attack on the city that has often been targeted by militants.

The loud blast erupted close to the NATO’s International Security Assistance Force (ISAF) headquarters and in an area of the capital that houses many embassies and international institutions.

ISAF confirmed that the explosion occurred outside their headquarters, while the US embassy sounded its emergency “duck and cover” sirens to warn employees to seek shelter.

“It was an accident, not an enemy act,” Lutfullah Mashal, an official from the National Directorate of Security (NDS) intelligence agency, told AFP.

“The blast happened in a depot for unexploded ordinance. It was totally an accident. There is no reported casualties, but there are some damages.”

The NDS said in a statement said that the depot contained explosives recently seized from insurgents and due to be taken to the Disbandment of Illegal Armed Group (DIAG) programme, which destroys illegal weapons and explosives.

An NDS spokesman told local television that the depot stored suicide vests, explosives and unexploded bombs.

The interior ministry also confirmed the explosion was an accident.

The blast came a day after a Taliban suicide bomber detonated an explosives-laden vehicle near a NATO military convoy entering Kabul airport, killing himself but causing no other deaths or injuries.

The airport houses another NATO base as well as operating civilian flights to cities including Dubai, New Delhi and Istanbul. Flights were delayed only briefly after the bomb exploded.

The Taliban, who regularly exaggerate casualty numbers, claimed responsibility via their main Twitter account for that attack, saying ten soldiers had been killed or injured.

Kabul has seen a recent drop in insurgent attacks after a series of high-profile strikes earlier this year, with the NDS claiming to have foiled several plots to launch complex strikes involving truck bombs and suicide gunmen.

A series of attacks earlier this year targeted foreign compounds, the Supreme Court, the airport and the presidential palace in the city.

NATO forces are withdrawing from Afghanistan after more than a decade of fighting the Taliban, but negotiations have stalled on a security accord that would allow some US and NATO troops to stay after 2014.

President Hamid Karzai was due to travel to India on Thursday, with US officials expressing hope that the Delhi government would be able to persuade him to sign the accord.