NEW DELHI — India used small boats this weekend to ferry some of its citizens to a naval destroyer anchored near Aden, Yemen, as an operation to evacuate about 4,000 Indians from Yemen’s war zone entered a difficult phase.

The Indian ship was not able to dock in Aden because of shelling, so the small boats carried people in groups of about 30, said Syed Akbaruddin, the spokesman for India’s External Affairs Ministry. About 2,000 Indians have now been transported out of Yemen, but the deteriorating conditions there mean that no more evacuations from Aden will be possible, he said.

“It’s been a hard task, and as the situation worsens, the time available to us lessens,” he said. “Difficult situations now are becoming more difficult as time passes.”

Several thousand Indian women work as nurses in Yemen, and many have been reluctant to leave, despite the intensifying conflict, because their families are so heavily dependent on their remittances.