China on Thursday pledged financial aid to Cuba as it undertakes historic economic reforms, promising visiting President Raul Castro a new credit line as well as help in health care and technology.

The offers were announced after a meeting between Castro and Chinese President Hu Jintao during which the two leaders spoke warmly about the strong ties between the longtime communist allies.

"We are very pleased that in recent years, the relationship between China and Cuba has continued to deepen and develop," Castro told Hu in brief comments before the media.

Hu highlighted the fact he had visited Cuba three times, and said he appreciated Castro's efforts in building relations with China.

After their meeting, the two sides said they had signed eight agreements aimed at deepening economic and political ties.

These included promises by China of financial aid, an interest-free loan and a credit-line to Cuba to help the country in a range of sectors, including technology and health care.

Few other details, including the sizes of the loans and aid, were given.

Castro's four-day visit to China, which began on Wednesday, comes at a crucial time for Cuba as it is in the throes of overhauling its economy towards a system that incorporates elements of capitalism.

China has embarked on an economic reform programme over recent decades that has achieved stunning results, and analysts said Castro's visit would also be a good opportunity for him to survey the Chinese success story.

"Cuba can learn many things from other socialist countries that have been economically successful, like China," said Yang Jianmin, a deputy director of the Center for Cuban Studies at the Chinese Academy of Social Sciences.

Yang said some of the most notable reforms Cuba could look at were in areas such as market stability, exports, investment and requirements needed to open companies.

"These experiences can help Cuba in their process of opening-up and generate many opportunities," he said.

Castro is slated to meet China's two leaders-in-waiting, Xi Jinping and Li Keqiang, on Friday, helping to deepen personal ties with the men widely expected to assume the Chinese presidency and premiership.

His visit to China follows Xi's trip to Havana last year when the two sides signed 10 deals aimed at supporting Cuba's economic reforms.

China is Cuba's top trading partner after Venezuela, with bilateral trade worth $1.8 billion a year. And even before Thursday's announcement, China had been a vital source of credit for the cash-strapped communist island.

The countries' close relationship dates back to 1960 when Cuba formally recognised communist rule in Beijing.

Ties grew even closer after the disintegration of the Soviet Union in 1991, which precipitated Cuba's downward economic spiral from which the country is still trying to recover.

Castro is being accompanied on his Asia trip by Foreign Minister Bruno Rodriguez and Ricardo Cabrisas, vice chairman of Cuba's council of ministers, the official Granma newspaper in Havana reported this week.

The Cuban delegation is then expected to travel to Vietnam, another communist ally that has like China embarked on a successful economic transformation by incorporating capitalist elements.

Vietnam is also an important economic partner for Cuba, particularly in the agricultural sector.

The Southeast Asian nation is Cuba's main supplier of rice, a staple food item on the island. Bilateral trade totaled $269 million in 2010, according to official statistics.